No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Part of a Letter from Mr Antony van Leeuwenhoek, F. R. S. concerning Green Weeds Growing in Water, and Some Animalcula Found about Them
Abstract
I Have often heard the Common People say, that that Green Stuff or Weeds which are observed to drive upon the Water spring out of the Ground from under the Water.
... Once a Hydra body is built, sensors added, and external and internal information integrated, what kind of coordinated movement can be generated both with and without neurons? Despite possessing a simple nerve net, normal Hydra can perform some quite complex behaviors, including somersaulting end over end and moving like an inchworm (Leeuwenhoek 1703;Trembley et al. 1744;Passano and Mccullough 1963;Han et al. 2018) (Fig. 5). It also executes an elaborate feeding response in which it catches multiple prey (Artemia nauplii in the lab) with its tentacles, brings the captured prey towards its mouth (which opens with prey capture), and, finally, inserts the prey into its gastric cavity (Lenhoff 1961). ...
... This appears to be the case, as normal Hydra exhibit much more complex behavior than nervefree animals. Hydra with neurons execute multiple complex movements, including inchworming, somersaulting, and an elaborate feeding response (Leeuwenhoek 1703;Trembley et al. 1744;Lenhoff 1961;Passano and Mccullough 1963;Han et al. 2018). Each of these behaviors requires the coordination of its various body parts in space over minutes-long timescales. ...
The small freshwater cnidarian Hydra has been the subject of scientific inquiry for over 300 years due to its remarkable regenerative capacities and apparent immortality. More recently, Hydra has been recognized as an excellent model system within neuroscience because of its small size, transparency, and simple nervous system, which allow high-resolution imaging of its entire nerve net while behaving. In less than a decade, studies of Hydra’s nervous system have yielded insights into the activity of neural circuits in vivo unobtainable in most other animals. In addition to these unique attributes, there is yet another lesser-known feature of Hydra that makes it even more intriguing: it does not require its neural hardware to live. The extraordinary ability to survive the removal and replacement of its entire nervous system makes Hydra uniquely suited to address the question of what neurons add to an extant organism. Here, I will review what early work on nerve-free Hydra reveals about the potential role of the nervous system in these animals and point towards future directions for this work.
... The Dutch microbiological pioneer Antonie van Leeuwenhoek discovered Hydra in 1702. In his letter to the Royal Society of London, he described finding a number of 'animalcula' attached to the roots of 'green weeds' he had pulled out of a river in what was then called the Low Countries [15]. These particular 'animalcula' appeared to contract and elongate, produce 'young animalcula' from their sides, and draw small 'wheels' in and out of their bodies. ...
As one of the first model systems in biology, the basal metazoan Hydra has been revealing fundamental features of living systems since it was first discovered by Antonie van Leeuwenhoek in the early eighteenth century. While it has become well-established within cell and developmental biology, this tiny freshwater polyp is only now being re-introduced to modern neuroscience where it has already produced a curious finding: the presence of low-frequency spontaneous neural oscillations at the same frequency as those found in the default mode network in the human brain. Surprisingly, increasing evidence suggests such spontaneous electrical low-frequency oscillations (SELFOs) are found across the wide diversity of life on Earth, from bacteria to humans. This paper reviews the evidence for SELFOs in diverse phyla, beginning with the importance of their discovery in Hydra , and hypothesizes a potential role as electrical organism organizers, which supports a growing literature on the role of bioelectricity as a ‘template’ for developmental memory in organism regeneration.
This article is part of the theme issue ‘Basal cognition: conceptual tools and the view from the single cell’.
... Hydra [17] exhibits many movements, including elongation and bending of the body column, ''nodding'' (i.e., bending just below the tentacles) [18], and contraction of tentacles [19] or the entire body column [20]. These movements can be strung together into behaviors such as the contraction burst [20], locomotion, including somersaulting and inchworm motions [21], and feeding, a behavior that includes opening the mouth and tentacular sweeping to ingest prey [22]. ...
Hydra is a cnidarian polyp with an anatomically simple neuromuscular system that can offer evolutionary insights on the functional design of animal body plans. Using calcium imaging to map the activity of the entire epitheliomuscular system of behaving Hydra, we find seven basic spatiotemporal patterns of muscle activity. Patterns include global and local activation events with widely varying kinetics of initiation and wave-like propagation. The orthogonally oriented endodermal and ectodermal muscle fibers are jointly activated during longitudinal contractions. Individual epitheliomuscular cells can participate in multiple patterns, even with very different kinetics. This cellular multifunctionality could enable the structurally simple epitheliomuscular tissue of basal metazoans to implement a diverse behavioral output.
... Spoznaja o važnosti fitoplanktona u Zemljinoj hidrosferi pojavila se tek nakon otkrića mikroskopa i mikroorganizama početkom 18. stoljeća (Van Leeuwenhoek, 1703.). U prvoj polovici 19. ...
Mikroorganizmi u oceanima koji fotosintezom stvaraju novu organsku tvar (fitoplankton) primarni su proizvođaći organske tvari te uz kopnenu vegetaciju reguliraju kruženje ugljika u biosferi i klimatske promjene na Zemlji. Istraživanje i poznavanje fitoplanktona u moru ulazi u domenu biološke oceanografije. Zbog povijesnih okolnosti, istraživanja fitoplanktona u Jadranu su započela odmah nakon početaka oceanografskih istraživanja u Europi u 19. stoljeću. Nakon razdoblja istraživanja klasičnim metodama, suvremena istraživanja u oceanografiji razvijaju se u drugoj polovici 20. stoljeća nakon pojave senzora koji opskrbljuju istraživače velikim brojem podataka i prijenosu podataka satelitima. Zahvaljujući biooptičkim svojstvima fitoplanktonskih stanica i mogućnošću mjerenja pigmenata biomarkera, senzorima se procjenjuje primarna biomasa i procesi u moru. Posljednje se razvijaju molekularne metode, koje otkrivaju evolucijske odnose i provjeravaju spoznaje koje je ponudila klasična taksonomija. Promjene koje danas zapisujemo bit će važna informacija budućim generacijama koje će na osnovu dužeg niza podataka moći sastaviti potpunije modele procesa u biosferi.
... These interesting organisms were firstly. studied and described hy Leeuwenhoek (1703) following the invention of the microscope. Since then, they have drawn world-wide attention of large number or naturalists as well as specialists because of their intricate structure, widespread distribution and endless profusion of body shapes. ...
... The rotifers have attracted the attention of the microscopists from different parts of the globe since they were first described by Leeuwenhoek (1703). The systematic studies on Indian Rotifera were, however, initiated by Anderson (1889) and so far resulted in about 105 publications from widely scattered localities in this country but still reflected lack of comprehensive regional or statewise faunistic investigations (Sharma, 1991). ...
... First of all, the recognition of such microorganisms as being plant-like was not straightforward. They were sometimes associated with animal life forms as Animalcules, a word popularized by Van Leeuwenhoek (1702) or Infusoria (Marchand 1869). In light of broad morphological similarities, some microalgae (especially the green Chlorophyceae) were mistaken for gametes produced by macroalgae (Gay 1891;Kützing 1844). ...
Algae have traditionally been included in the group Cryptogamae ('hidden reproduction'), as opposed to Phanerogamae or Spermatophyta, the Seed Plants. Cryptogamae encompassed both macro-and microalgae, lichens, mosses, and ferns, and have also been referred to as 'Thallophyta', 'non-vascular plants', 'spore plants', seedless or fl owerless plants, depending on the criteria used for classifi cation. Microalgae have long been considered among the more primitive and less important organisms representing the plant-like characters of autotrophy and immobility. Reproduction in macroalgae was only observed in the 18th century, but the ability of microalgae to reproduce sexually was not demonstrated until the 19th century in microscopic green fi lamentous algae. In this chapter, we summarise up-to-date information on sexual reproduction in three major groups of 2 Reproductive Biology of Plants microalgae, the diatoms, dinofl agellates and haptophytes, and discuss its relationship to biodiversity and ecological life cycle strategies. Microalgae obviously constitute the microscopic part of the 'plant-like' world, but they do not deserve being considered lower 'plants', as they exhibit a perplexing diversity of modalities of sexual reproduction (haplontic, haplo-diplontic, diplontic life cycles), compared to the 'higher plants' which appear strikingly uniform and rather limited in their life cycle options.
... Bdelloid rotifers are microscopic, aquatic animals often considered an evolutionary scandal because they have apparently evolved asexually for more than 60 Myr [1]. Evidence for their long-term evolution and diversification in the absence of conventional sex (here defined as the alternation of meiosis and fertilization events) has accumulated since their first observation by Van Leeuwenhoek [2] and has recently been summarized by Fontaneto and Barraclough [3]. Earlier cytological studies on two bdelloid species described egg production by two maturation divisions from primary oocytes without chromosome pairing or reduction in chromosome number [4,5]. ...
Although strict asexuality is supposed to be an evolutionary dead end, morphological, cytogenetic, and genomic data suggest that bdelloid rotifers, a clade of microscopic animals, have persisted and diversified for more than 60 Myr in an ameiotic fashion. Moreover, the genome of bdelloids of the genus Adineta comprises 8%-10% of genes of putative non-metazoan origin, indicating that horizontal gene transfers are frequent within this group and suggesting that this mechanism may also promote genetic exchanges among bdelloids as well. To test this hypothesis, we used five independent sequence markers to study the genetic diversity of 576 Adineta vaga individuals from a park in Belgium. Haplowebs and GMYC analyses revealed the existence of six species among our sampled A. vaga individuals, with strong evidence of both intra- and interspecific recombination. Comparison of genomic regions of three allele-sharing individuals further revealed signatures of genetic exchanges scattered among regions evolving asexually. Our findings suggest that bdelloids evolve asexually but exchange DNA horizontally both within and between species.
... However the mechanisms that dictate the relation between past exposure and degradation rate have not been elucidated. Microorganisms and in particular bacteria have been studied in a number of ways through history starting from observation with magnifying glass by Antony van Leeuwenhoek back in the 17th century (Van leeuwenhoek, 1702) to arrive to newly-developed high-output DNA sequencing (Gobet et al., 2012). Different methods measure different parameters (e.g. ...
... Among them, the diatoms (Bacillariophyta, Diatomeae, Figure 4.) are typically present in all, except the hottest and most hypersaline habitats, and during all seasons throughout the globe (Round et al., 1990). Having silica walls with very distinctive ornamentation, diatoms were recognized very early on (Leeuwenhoek, 1703) gaining one of the most comprehensive data records among all microorganisms. Being easy to collect and preserve in permanent slides, diatoms have gained much attention regarding pollution/eutrophication monitoring, or various others indications such as salinity, acidity, pH value, Al concentrations, dissolved organic carbon and humic substances (Schönfelder, 2000). ...
... One candidate is the freshwater polyp, Hydra [17]. Hydra has been studied for over 300 years [18,19], mainly for its profound ability to regenerate (for a review, see [20]). It is a freshwater radial-symmetric predator (Phylum Cnidarian; Class Hydrozoa) which diverged from Anthozoans >540 million years ago, placing it at the basal root of animal life. ...
In this paper we contrast the simple role of FOXO in the seemingly non‐aging Hydra with its more diversified function in multicellular eukaryotes that manifest aging and limited life spans. From this comparison we develop the concept that, whilst once devoted to life‐prolonging cell‐renewal (in Hydra), evolutionary accumulation of coupled functionality in FOXO has since ‘distracted’ it from this role. Seen in this light, aging may not be the direct cost of competing functions, such as reproduction or growth, but the result of a shift in emphasis in a protein, which is accompanied by advantages such as greater organismal complexity and adaptability, but also disadvantages such as reduced regeneration capacity. Studying the role of FOXO in non‐aging organisms might, therefore, illuminate the path to extend life span in aging organisms.
Editor's suggested further reading in BioEssays Stem cells and aging from a quasi‐immortal point of view Abstract
... Observations on the ciliates associated with hydra are as old as the discovery of the polyp itself: they were seen by Leeuwenhoek (1703), remarked upon and illustrated by Trembley (1744), Rosel (1754) and others, and recorded with great care by Ehrenberg (1835Ehrenberg ( ,1838 and Stein (1854Stein ( ,1859 Ehrenberg, 1838. These often occur together on the same hydra. ...
Epizoic Kerona pediculus have been found on Hydra vulgaris and on Cristatella mucedo (Bryozoa) in the same habitat. On the basis of morphological characters (using Nomarski and Scanning Electron Microscopy) specimens from the two hosts are indistinguishable. Details revealed by SEM agree with previous results from silver staining, confirming the identity of K. pediculus. The taxonomic status of this species is briefly summarised. Host recognition, the inhibition of nematocyst discharge, and the possible role of host growth-promoting substances are not yet understood.
... During the first period, Leeuwenhoek (1704) described the form, the budding and the behaviour of hydras, to which he named "animalcules". Baker (1743) published a book describing the natural history of three different types of hydras, one of which became a new one, the type of the green hydras. ...
This is the former contribution of a series of studies related to the composition of the genus Hydra in Argentina. The taxon analyzed constitutes a new subspecies found in the shallow lake Los Padres (General Pueyrredón district, Buenos Aires province). All the specimens analyzed exhibited the typical characteristics of the group vulgaris, which belongs to the species Hydra vulgaris Pallas, 1766. They also display a prominent stalk near the foot, being this one a new morphological character for the species.
... Although diatoms have been observed with light microscopy for over 275 years (Anonymous 1703, Leeuwenhoek 1703) and with electron microscopy for over 50 years (Krause 1936), little is known about genealogical relationships in some groups, particularly at the generic level. Many authors have investigated relationships at this level of hierarchy; however , more recent works have concentrated almost exclusively on marine and freshwater centric dia- toms. ...
Relationships among the apical pore field-bearing diatom genera Brebissonia, Cymbella, Gomphonema, Gomphoneis, Didymosphenia, Gomphocymbella, and Reimeria and their close ally Encyonema were evaluated using cladistics. These biraphid genera are a polythetic group defined by chloroplast number and type, mode of sexual reproduction, valve orientation and presence of apical pore fields. Character states of valve as well as non-siliceous features were described and then polarized using the outgroup method, with the naviculoid genera Anomoeoneis and Placoneis serving as outgroups. The cladistic analysis suggests two groups of terminal taxa, corresponding to to a predominantly cymbelloid lineage and a gomphonemoid lineage. Didymosphenia, previously thought to be closely allied to gomphonemoid diatoms, is shown to be more closely related to Cymbella. Gomphonema appears to be without distinguishing characteristics. Relationships of the other genera are described. The systematic position of small, doubly-punctate Gomphonema species is discussed.
... Diatoms were apparently first recorded by someone known only as Mr. C., a fellow of the Royal Society, in the November–December issue of Philosophical Transactions for 1703 (Anonymous, 1703). It was penned in response to a letter from the noted Dutch microscopist Antonie van Leeuwenhoek (1632–1723), who appears to have recorded the existence of diatoms a little earlier (Leeuwenhoek, 1703). The organism Leeuwenhoek noted moved around and thus he assumed it to be an animal rather than a plant. ...
Diatoms were apparently first recorded by someone known only as Mr. C., a fellow of the Royal Society, in the November–December
issue of Philosophical Transactions for 1703 (Anonymous, 1703). It was penned in response to a letter from the noted Dutch microscopist Antonie van Leeuwenhoek
(1632–1723), who appears to have recorded the existence of diatoms a little earlier (Leeuwenhoek, 1703).
KeywordsCharacters-Cladistics-Classification-Molecules-Monophyly-Morphology-Palaeontology-Phylogeny-Reproduction-Taxonomy-Taxon numbers
The politicization of science – the infusion of ideology into the scientific enterprise – threatens the ability of science to serve humanity. Today, the greatest such threat comes from a set of ideological viewpoints collectively referred to as Critical Social Justice (CSJ). This contribution describes how CSJ has detrimentally affected scientific publishing by means of social engineering, censorship, and the suppression of scholarship.
Throughout the Histoire naturelle Buffon was ever aware of epistemological issues involving the reproduction of species, the only beings in nature. By the 1760s he had come to believe that empirical evidence, the source of all human knowledge, revealed that reproduction was a physical process, involving a common living (minute, active, and lively) matter and material forces, all of which he traced to the foundational force of gravitational attraction.
In the first half of the nineteenth century it was commonly supposed that new cells arose either exogenously, outside pre-existing cells, or endogenously, from small rudiments that appeared within pre-existing cells and gradually grew larger. The theory of exogeny had been founded by Wolff (1759), and was supported especially by Link (1807), Schwann (1839), and Vogt (1842). The theory of endogeny, which had been hinted at by various writers in early times, obtained the backing of a very large literature. Its chief advocates were Raspail (1825, &c), Turpin (1827, &c), Schleiden (1838), Kölliker (1843-4), and Goodsir (1845).
That cells do not arise exogenously or endogenously, but are produced by the division of pre-existing cells, was at last realized by the convergence of studies made in three separate fields, as follows :
(1) Trembley (1746, &c), Morren (1830, 1836), Ehrenberg (1830, 1832, 1838), and others noticed how protists multiply.
(2) Dumortier (1832), Mohl (1837), and Meyen (1838) watched the partitioning of the cells of filamentous algae.
(3) Several observers studied the cleavage of eggs and at last revealed that this was a process of cell-division (Prevost and Dumas (1824), von Siebold (1837), Barry (1839), Reichert (1840), Bagge (1841), Bergmann (1841-2)).
Nägeli (1844, 1846) also made an important study of cell-division in all the main groups ofplants (except bacteria), but used an unfortunate nomenclature that tended to obscure the truenature of the process.
Remak (1852 and 1855) and Virchow (1852, 1855, 1859) made general statements to the effect that division is the standard method by which cells multiply. The writings of Remak on this subject were much more weighty than those of Virchow.
The entomopathogenic nematode, Heterorhabditis indica, is a popular biocontrol agent of high commercial significance. It possesses tremendous genetic architecture to survive desiccation stress by undergoing anhydrobiosis to increase its lifespan-an attribute exploited in the formulation technology. The comparative transcriptome of unstressed and anhydrobiotic H. indica revealed several previously concealed metabolic events crucial for adapting towards the moisture stress. During the induction of anhydrobiosis in the infective juveniles (IJ), 1584 transcripts were upregulated and 340 downregulated. As a strategy towards anhydrobiotic survival, the IJ showed activation of several genes critical to antioxidant defense, detoxification pathways, signal transduction, unfolded protein response and molecular chaperones and ubiquitin-proteasome system. Differential expression of several genes involved in gluconeogenesis - β-oxidation of fatty acids, glyoxylate pathway; glyceroneogenesis; fatty acid biosynthesis; amino-acid metabolism - shikimate pathway, sachharopine pathway, kyneurine pathway, lysine biosynthesis; one-carbon metabolism-polyamine pathway, transsulfuration pathway, folate cycle, methionine cycle, nucleotide biosynthesis; mevalonate pathway; and glyceraldehyde-3-phosphate dehydrogenase were also observed. We report the role of shikimate pathway, sachharopine pathway and glyceroneogenesis in anhydrobiotes, and seven classes of repeat proteins, specifically in H. indica for the first time. These results provide insights into anhydrobiotic survival strategies which can be utilized to strengthen the development of novel formulations with enhanced and sustained shelf-life.
Within a few months of the year 1741, Lyonet and Trembley in Holland, Bonnet in Geneva and Réaumur in Paris all experimented industriously with the regeneration of various invertebrates, including the still unknown microdrile oligochaetes. Some of these worms were prone to spontaneous fragmentation as a natural mode of asexual multiplication, preceded (paratomy) or followed (architomy) by regenerative processes. Bonnet and Réaumur raised the stakes and began to study regeneration in earthworms, a challenge that, especially in Italy, inspired scholars and educated people among the clergy and aristocracy. Spallanzani conducted the most rigorous experiments and was the first to obtain consecutive regenerations of the head in one and the same megadrile. He saw detached mid-body sections becoming complete with a new head and a new tail, and he determined the points of the body where regeneration does not take place and how much length to leave for each section so that it could reintegrate. Above all, Spallanzani obtained regeneration of the gonadic segments, both in terrestrial and in freshwater megadriles, the latter today identified as Criodrilus lacuum. This and other important anatomical and physiological findings by Spallanzani, largely unpublished during his lifetime and for a long time after, preceded the discoveries of later authors by almost 50 years.
Although gradual deterioration of life functions with age is not a fundamental rule, it is pervasive among living organisms, regardless of their mode of reproduction and the number of constituent cells. However, deterioration can be temporarily arrested or slowed down due to the process of anhydrobiosis. Two modes of anhydrobiosis can be distinguished for the developmental and adult stages of animals. Developmental resting stages are reported for different animals, including sponges (Porifera), stingers (Cnidaria), flatworms (Platyhelminthes), insects (Insecta), copepods (Copepoda) and branchiopods (Branchiopoda). However, anhydrobiosis occurring at any stage of animal life, including adults, is found only in a few invertebrate phyla, namely roundworms (Nematoda), wheel animals (Rotifera) and water bears (Tardigrada). Notably, in the second group anhydrobiosis has been proposed to eliminate or slow‐down aging symptoms. This, in turn, may correlate with higher fitness and fecundity, and increased offspring longevity. We present available data concerning anhydrobiosis of tardigrades, bdelloid rotifers and nematodes, the only animals known to be capable of anhydrobiosis as adult individuals. The impact of anhydrobiosis on animal aging is illustrated by two models based on experimental data, namely the “Sleeping Beauty” and “Picture of Dorian Grey” models. According to the “Sleeping Beauty” model, anhydrobiotic organisms do not age during anhydrobiosis, whereas the “Picture of Dorian Grey” model predicts that the anhydrobiotic organism ages, at least during the initial stage of anhydrobiosis. Finally, we discuss possible implications of these models for individual longevity and survival as well as phenotypic diversity of taxa and their evolution. A better understanding of life strategies of anhydrobiotic animals both at the ontogenetic and phylogenetic levels can provide answers to many fundamental questions and useful practical outputs in branches of applied sciences.
A microbe is a microscopic organism which may exists in its single-celled form or in a colony of cells. In recent years, accumulating researchers have been engaged in the field of uncovering microbe-disease associations since microbes are found to be closely related to the prevention, diagnosis, and treatment of many complex human diseases. As an effective supplement to the traditional experiment, more and more computational models based on various algorithms have been proposed for microbe-disease association prediction to improve efficiency and cost savings. In this work, we developed a novel predictive model of Graph Regularized Non-negative Matrix Factorization for Human Microbe-Disease Association prediction (GRNMFHMDA). Initially, microbe similarity and disease similarity were constructed on the basis of the symptom-based disease similarity and Gaussian interaction profile kernel similarity for microbes and diseases. Subsequently, it is worth noting that we utilized a preprocessing step in which unknown microbe-disease pairs were assigned associated likelihood scores to avoid the possible negative impact on the prediction performance. Finally, we implemented a graph regularized non-negative matrix factorization framework to identify potential associations for all diseases simultaneously. To assess the performance of our model, cross validations including global leave-one-out cross validation (LOOCV) and local LOOCV were implemented. The AUCs of 0.8715 (global LOOCV) and 0.7898 (local LOOCV) proved the reliable performance of our computational model. In addition, we carried out two types of case studies on three different human diseases to further analyze the prediction performance of GRNMFHMDA, in which most of the top 10 predicted disease-related microbes were verified by database HMDAD or experimental literatures.
Compared to larger lakes, ponds have rarely been the focus of palaeoecological studies. A common feature of ponds, especially those subject to eutrophication, is mass surface coverings of lemnoid Araceae (duckweed) which have severe implications for ecological processes in small waterbodies, in particular lowered oxygen content. To help understand the implications of duckweed dominance for the long-term ecology of ponds, and to determine the potential for palaeoecological studies in ponds more generally, we develop a new diatom-based Lemna-indicator metric. Recent studies of diatom host-plant relationships have shown significant associations between duckweed and the epiphytes Lemnicola hungarica and Sellaphora saugerresii (formally known as Sellaphora seminulum). To determine the potential of these species as palaeo-indicators of long-term duckweed dynamics in ponds, we investigated the diatom composition of surface sediment assemblages in sets of duckweed and non-duckweed-dominated ponds in Norfolk, eastern England. In addition, we undertook diatom analysis of two cores from a small farmland pond (Bodham Rail Pit) subject to a known duckweed dominance event (1999–2005). Both L. hungarica and S. saugerresii were significant predictors of past Lemna dominance in the surface sediments. Further, in the core study, both diatom species accurately and closely tracked the documented “on–off” duckweed cycle. Our study suggests huge potential for using ponds in palaeoecological studies and for diatom-based investigations of floating plant histories.
Objectives: The aim of this study was to determine if it is possible to establish and maintain a binary biofilm consisting of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, which could be used as a multi-species model for antibiotic action studies.
Materials & Methods: A medium controlled, continuous culture biofilm model was developed based upon the previously developed Sorbarod™ model. This new model was designed to enable the growth of B. subtilis and E. coli at the same time without either out-competing the other.
Results: A pseudo-steady-state binary biofilm was established, which could be maintained for a total of 53 hours. This biofilm was tested to confirm the ability of the biofilm model to support the growth of a Gram-positive (Bacillus subtilis) and a Gram-negative (Escherichia coli) bacterial species under the same conditions of media throughput, aeration and temperature.
Conclusions: This paper gives evidence of the ability to develop and control binary biofilm models to maintain the growth of two Gram-dissimilar species of bacteria. We believe this is a novel concept and will aid the future in vitro assessment of antibiotic activity in coinfection models.
Mapping whole-brain activity during behavior represents one of the biggest and most exciting challenges of systems neuroscience. New research has taken advantage of the unique biology of an ancient organism to bring us a step closer to that goal.
To understand the emergent properties of neural circuits, it would be ideal to record the activity of every neuron in a behaving animal and decode how it relates to behavior. We have achieved this with the cnidarian Hydra vulgaris, using calcium imaging of genetically engineered animals to measure the activity of essentially all of its neurons. Although the nervous system of Hydra is traditionally described as a simple nerve net, we surprisingly find instead a series of functional networks that are anatomically non-overlapping and are associated with specific behaviors. Three major functional networks extend through the entire animal and are activated selectively during longitudinal contractions, elongations in response to light, and radial contractions, whereas an additional network is located near the hypostome and is active during nodding. These results demonstrate the functional sophistication of apparently simple nerve nets, and the potential of Hydra and other basal metazoans as a model system for neural circuit studies.
The Hydra monster lurking beneath the waters of the Halcyon Lake of ancient Lerna, which figured as one of the heroic exploits of Hercules in Greek mythology, was credited with attributes of toxicity and curative regenerative abilities, offering a remarkable prototype for the freshwater invertebrate polyp that resembles its appearance and bears its name in scientific nomenclature. The resemblance, however, is fortuitous since the animal’s characteristics are not observable to the unaided eye and it was unknown to the Classical world. The mythical Hydra was a zoomorphism of a psychoactive drug that figured in the very ancient Mystery rites that were still being enacted at the sacred lake well into Roman times, when the original offering of human victims was replaced by initiatory experiences of spiritual transcendence.
Diatoms commonly called as “Jewels of Sea” are very intricate and beautiful microscopic photosynthetic algae. They make up approximately 90 % of all living organisms in sea and they are expected to produce 20 – 40 % oxygen of earth’s atmosphere. They have distinct cell wall which is silicified and hence called “Algae in Glass house”. There are approximately 20,000 – 2 million species which are present in diverse habitat. They not only photosynthesize and produce O2 but because of this they are able to store lipids and are being considered as a new promising source of biofuel. In the present chapter an attempt has been made to discuss the detailed ecology, classification, structure and reproduction of diatoms.
Microbiology is the part of science linked with the study of microorganisms and their properties. Since its beginnings in the XV IIth century, the methods developped by the microbiologists revealed a huge potential of knowledge and applications.In the last decades, industrials realized the interests of this study areaThe need to prevent contaminations by inhibiting microbial development, or on the contrary the will to improve it to enjoy the chemical transformations capacities of the microorganisms gave birth to an increasing demand for microbiological tests. The poor yield of traditionnal methods does not allow to satisfy this need, and the search for new test methods is thus focalizing interests. Miniaturized fluidic tools have already proven their potential for this kind of applications, and yet, their validation towards traditionnal methods often lacks.In this work, we aim at developping miniaturized cultivation techniques and optimized growth analysis methods, to study the scale reduction impact of incubator's size on growth, in order to end up with a high-throughput tool for biocide caracterization.
The disaccharide sugar trehalose is essential for desiccation resistance in most metazoans that survive dryness; however, neither trehalose nor the enzymes involved in its metabolism have ever been detected in bdelloid rotifers despite their extreme resistance to desiccation. Here we screened the genome of the bdelloid rotifer Adineta vaga for genes involved in trehalose metabolism. We discovered a total of four putative trehalose-6-phosphate synthase (TPS) and seven putative trehalase (TRE) gene copies in the genome of this ameiotic organism; however, no trehalose-6-phosphate phosphatase (TPP) gene or domain was detected. The four TPS copies of A . vaga appear more closely related to plant and fungi proteins, as well as to some protists, whereas the seven TRE copies fall in bacterial clades. Therefore, A . vaga likely acquired its trehalose biosynthesis and hydrolysis genes by horizontal gene transfers. Nearly all residues important for substrate binding in the predicted TPS domains are highly conserved, supporting the hypothesis that several copies of the genes might be functional. Besides, RNAseq library screening showed that trehalase genes were highly expressed compared to TPS genes, explaining probably why trehalose had not been detected in previous studies of bdelloids. A strong overexpression of their TPS genes was observed when bdelloids enter desiccation, suggesting a possible signaling role of trehalose-6-phosphate or trehalose in this process.
Leeuwenhoek's 1677 paper, the famous ‘letter on the protozoa’, gives the first detailed description of protists and bacteria living in a range of environments. The colloquial, diaristic style conceals the workings of a startlingly original experimental mind. Later scientists could not match the resolution and clarity of Leeuwenhoek's microscopes, so his discoveries were doubted or even dismissed over the following centuries, limiting their direct influence on the history of biology; but work in the twentieth century confirmed Leeuwenhoek's discovery of bacterial cells, with a resolution of less than 1 µm. Leeuwenhoek delighted most in the forms, interactions and behaviour of his little ‘animalcules', which inhabited a previously unimagined microcosmos. In these reflections on the scientific reach of Leeuwenhoek's ideas and observations, I equate his questions with the preoccupations of our genomic era: what is the nature of Leeuwenhoek's animalcules, where do they come from, how do they relate to each other? Even with the powerful tools of modern biology, the answers are far from resolved—these questions still challenge our understanding of microbial evolution. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions
of the Royal Society.
Microbial metabolomes gain more and more attention due to the fact that microorganisms are ubiquitous and important in environment and health. Some are involved in basic environmental processes and govern element cycles in the entire ecosystem; others have relevance for animals and human (as commensal or pathogens) and have the potential to be used in biotechnology. The tools of Metabolomics have been used for many years in microbial research and the paradigm is changing from studies on single species cultures to multispecies communities, like in biofilms or environmental and human microbiomes. These changes lead to a new variety of metabolomic tools (metametabolomics) adapted to the study of multiple organisms systems. In addition the needs in high-resolution instrumentation are changing to analytical platforms that enable to deal with the yet unknown compounds. ICR-FT/MS is a promising ultrahigh resolution mass spectrometry approach mastering the challenge in non-targeted metabolomics. This chapter presents an introduction to the current state of the art in microbial metabolomics, the importance of ICR-FT/MS in this field and is describing solutions for non-targeted metabolomics with a focus on bacterial samples. © 2012 Springer Science+Business Media, LLC. All rights are reserved.
In light of WFD (Water Framework Directive) guidelines for freshwater monitoring, this paper addresses the suggested organisms to be used in regular biomonitoring systems. Based on critical observations and reported obstacles in applying the various developed methods, but also on long-term research on freshwater ecosystems in Macedonia, the best bioindicator organism is proposed. In order to have an overall assessment of the investigated ecosystem, biomonitoring organisms (such as fish, macrophytes) or geomorphology reveal important informations. But, if the target is rapid, reliable, and cost effective bioindication of the water quality (with algae and benthic invertebrates only) have a most comprehensive application in history. Accumulated evidence that using benthic invertebrates pose a problem in obtaining reliable results triggered a recent CEN's revision of their applicability in monitoring programs. Therefore, amid all critically addressed disadvantages, algae (benthic diatoms in particular) are recommented as the best solution and basic methodology given for being included in regular bioindication programs in rapid detection of water quality of lotic and lenthic freshwater environments.
We define an organismic biologist as one whose research is focused primarily on a single organism, or group of related organisms, and who investigates virtually the whole of nature as lived by that organism. We contrast an organismic biologist with a problem-oriented biologist, that is one who uses an organism, or a group of organisms, in order to investigate a particular question. In our view, the consummate organismic biologist has an outlook that allows her or him to conduct research on organisms with an open eye, to follow the cues offered by the organism, and to switch and learn new disciplines when the challenge to understanding the particular organism leads the investigator in those directions. We provide examples of the organismic approach of Abraham Trembley working in the eighteenth century and of the senior author working in the twentieth century. Both focused their investigations mostly on the freshwater hydra. While studying hydra, Trembley demonstrated that: (a) complete animals can regenerate from small, cut pieces of those animals; (b) animals can reproduce asexually by budding; (c) tissue sections from two different animals of the same species can be grafted to each other; (d) the materials oozing out of the edges of cut tissue have properties that fit the definition of protoplasm as described by Dujardin one hundred years later; (e) living tissues can be stained, and those stained tissues can be used in experiments; and (f) “eyeless” animals can exhibit a behavioral response to light. Some of the topics investigated in hydra by the senior author and his students are: (a) behavioral responses to the peptide reduced glutathione and to tryosine; (b) mechanism of activation of the receptor to glutathione; (c) migration of nematocytes; (d) algal-animal endosymbiosis; (e) an unusual disulfide-linked collagen of nematocyst capsules; (f) components and action of nematocyst venom; (g) intracellular digestion of radioactive protein; (h) composition of and role in cellular adhesion of the mesoglea; and, (k) a developmental mutant and role of nerve cells in promoting budding. We conclude with a proposal for one way to train future organismic biologists at the graduate and post graduate levels. This proposal grew out of our perception of the need to provide environments that nurture scientists who, by studying organisms, will find and define new experimental systems for the next waves of biological discovery yet to come when the specialists begin to investigate even more intensively the interactions between cells, tissues, organisms, and communities. Specifically, we propose that on the campuses of several major universities having a broad range of graduate programs, there be established year-round Institutes for Organismic Marine Biology focused on the investigation of organisms not previously amenable to systematic experimentation. We believe that if America's biology is to remain vibrant and innovative, organismic biology should be an integral component in any long term planning for research and training in the biological sciences.
The Argument
Contrary to the dominant historiography of microscopy, which tends to maintain that there was no microscopical program in the Enlightenment, this paper argues that there was such a program and attempts to illustrate one aspect of its dynamic character. The experiments, observations, and interpretations on rotifers and their management by scholars of that period show that there did exist a precise axis of research that can be followed historically. Indeed, the various controversies these scholars engaged in imply that they performed accurate microscopical experiments and observations and also carefully interpreted their visual data. Furthermore, the kinds of phenomena presented by the rotifer and other microscopic entities, such as their morphology or their revival from desiccation, helped to improve methodology on the use of the microscope. The paper also argues that this sort of inquiry is not fundamentally different from other research in the natural sciences of the eighteenth century.
The name Hydra attenuata Pallas is currently applied to the wrong animal. The common brown polyp, which is widely called H. attenuata, was described by Pallas (1766) as Hydra vulgaris. The name H. attenuata Pallas originally referred to an uncommon pale polyp, currently known as H. circumcincta Schulze. The history of this confusion is analysed here. The taxonomy of hydra was in disarray during the 18th and 19th centuries, and was clarified in 1917 with the monograph of Schulze. But Schulze misapplied the name for the common hydra, H. vulgaris, to an unusual form and thus was led to assign the name of a rare hydra, H. attenuata, to the common type. Schulze redescribed the rare, pale hydra that Pallas had named H. attenuata as H. circumcincta. The correct name of the common European brown, stalkless hydra is thus H. vulgaris Pallas, 1766. The name H. attenuata has priority for the uncommon pale hydra, but because of disuse of this application of the name, the pale hydra should be recognized by the current, generally accepted binominal H. circumcincta Schulze, 1914.
The history of diatom research in The Netherlands and Flanders is summarized in this report. A. van Leeuwenhoek observed diatoms as early as 1702. The first inventories were made in The Netherlands by R. B. van den Bosch (1846) and in Flanders by J.-J. Kickx (1867). Diatoms were already used in geological research in the second half of the nineteenth century. The Synopsis by H. van Heurck (1880–1885) enabled many twentieth century workers to do applied research for geological and ecological purposes.
With reference to the author's compilation of British rotifer records, the main contributions to our knowledge of rotifers in the British Isles are outlined and the impetus provided by local natural history societies is commented upon. The usefulness and limitations of early records are examined and the scope offered to future collectors is discussed.
ResearchGate has not been able to resolve any references for this publication.