Development of the trophic structure of Vendian and Early Paleozoic marine communities

Major trophic links are reconstructed for the Vendian and Early Paleozoic. A hypothesis of the predominant development of extracorporeal or skin digestion in Vendian multicellular consumers is substantiated. The main food sources were algal-bacterial films, finely dispersed debris falling from the photic zone in cold shallow seas lacking a thermocline and debris on the surface of the sediment. Symbiosis with phototrophic and chemotrophic bacteria was widespread. Pelagic filtration and filtration of the near-bottom finely dispersed organic matter (including bacteria), and debris-feeding appeared when internal digestion became widespread in the Cambrian. These were supplemented in the Ordovician by feeding on the live phyto- and zooplankton in the water column one meter above the bottom. Before the Ordovician, feeding on live plankton and more so active predation on larger multicellular animals was the exception rather than the rule. The role of active predators in the biota did not become more important until the end of the Silurian. Mass morphogenesis among occurred multicellular animals as the amount and diversity of nutritional and/or spatial resources rapidly increased, while before that the lack of these was a limiting factor.     

Occurrence and patterns of antibiotic resistance in vertebrates off the Northeastern United States coast

The prevalence of antibiotic-resistant bacteria in the marine environment is a growing concern, but the degree to which marine mammals, seabirds and fish harbor these organisms is not well documented. This project sought to identify the occurrence and patterns of antibiotic resistance in bacteria isolated from vertebrates of coastal waters in the northeastern United States. Four hundred and seventy-two isolates of clinical interest were tested for resistance to a suite of 16 antibiotics. Fifty-eight percent were resistant to at least one antibiotic, while 43% were resistant to multiple antibiotics. A multiple antibiotic resistance index value ≥0.2 was observed in 38% of the resistant pathogens, suggesting exposure of the animals to bacteria from significantly contaminated sites. Groups of antibiotics were identified for which bacterial resistance commonly co-occurred. Antibiotic resistance was more widespread in bacteria isolated from seabirds than marine mammals, and was more widespread in stranded or bycaught marine mammals than live marine mammals. Structuring of resistance patterns based on sample type (live/stranded/bycaught) but not animal group (mammal/bird/fish) was observed. These data indicate that antibiotic resistance is widespread in marine vertebrates, and they may be important reservoirs of antibiotic-resistant bacteria in the marine environment.     

High abundance of virulence gene homologues in marine bacteria

Marine bacteria can cause harm to single-celled and multicellular eukaryotes. However, relatively little is known about the underlying genetic basis for marine bacterial interactions with higher organisms. We examined whole-genome sequences from a large number of marine bacteria for the prevalence of homologues to virulence genes and pathogenicity islands known from bacteria that are pathogenic to terrestrial animals and plants. As many as 60 out of 119 genomes of marine bacteria, with no known association to infectious disease, harboured genes of virulence-associated types III, IV, V and VI protein secretion systems. Type III secretion was relatively uncommon, while type IV was widespread among alphaproteobacteria (particularly among roseobacters) and type VI was primarily found among gammaproteobacteria. Other examples included homologues of the Yersinia murine toxin and a phage-related 'antifeeding' island. Analysis of the Global Ocean Sampling metagenomic data indicated that virulence genes were present in up to 8% of the planktonic bacteria, with highest values in productive waters. From a marine ecology perspective, expression of these widely distributed genes would indicate that some bacteria infect or even consume live cells, that is, generate a previously unrecognized flow of organic matter and nutrients directly from eukaryotes to bacteria.     

Appearance and evolution of marine benthic communities in the Early Palaeozoic

The development of marine benthic communities in the Early Palaeozoic occurred mainly in the shallow water epicontinental seas. It included those stages of the Cambrian and Ordovician evolutionary radiations that were dominated by a high rate of morphogenesis, when new food and territory resources were not limited. This provided many opportunities for coadaptation of emerging organisms. At the time of the Cambrian radiation, the body plans of all animals were formed, while in the Ordovician, the maximum rank of emerging taxa did not exceed the level of class. The beginning of each radiation was explosive. Vendian benthic communities developed in cold seas and in the shallowest areas of warm seas, where organic matter from the surface layers was available at the bottom because of the absence of a thermocline. The Cambrian radiation began with the appearance of pelagic suspension feeders, because of which much of the primary production could penetrate the thermocline and settle at the bottom. This allowed the occupation of warmer seas and greater depths. At the same time, the productivity of the pelagic region sharply increased because of the emergence of positive feedback between the producers and consumers in the water, leading to increased water transparency and elongation of trophic chains. Arthropods, the first suspension feeders, were the launch group of the Cambrian radiation. Cambrian benthic suspension feeders could seize only the smallest particles, mostly bacteria, and dissolved organic matter. This food resource was contained in the thin bottom water layer. Therefore, the food grasping structures of all the Cambrian suspension feeders were near the bottom, without forming tiers. The Ordovician evolutionary radiation began with the launch of the Pelmatozoan echinoderms, which were the first benthic suspension feeders to begin feeding on plankton. The exploitation of this resource led to the creation of a 1-m tier above the bottom and an increase in their calcite productivity. Positive feedback emerged between the grounds and the community of its inhabitants and considerably changed the composition and diversity of grounds, which sharply increased the diversity of benthos. The appearance of positive feedback between different components of ecosystems resulted in explosive evolution in both the Cambrian and Ordovician.     

From Vendian to Cambrian: the beginning of morphological disparity of modern metazoan phyla

Continuity of the transition from Precambrian to the Phanerozoic metazoan fauna at the phylum level is analyzed. The discrete traces of feeding on bacterial mats by Dickinsonia and similar organisms are explained by extracorporeal digestion, characteristic of a placozoan level of organization, as in the extant Trichoplax. The absence of a morphologically developed anterior end of the body, of food-gathering appendages of any kind, and of appendages responsible for movement suggest that these animals were at this level of organization. Probably, an expanded placozoan level of organization can be assumed for most Vendian animals. Against this background, new characters emerged in the Cambrian to be included in the body plan of extant animal phyla. The relationships between the morphological archetype (body plan) and morphogenetic archetype are considered. It is shown that major features of a morphogenetic archetype could be retained from the time the taxon was formed.     

Feeding traces of proarticulata—the Vendian metazoa

Three types of low-topography impressions are described from the Late Vendian, which are interpreted as the feeding traces of representatives of the phylum Proarticulata Fedonkin, 1985, which became extinct in the Precambrian. The producers of two types of trace were found. Impressions are usually large and arranged in groups; therefore their correct interpretation only became possible following large-scale excavation work that was carried out for the first time in the Late Vendian deposits of the Arkhangelsk Region in 1996–2001. The single trace (or trace platform) represents a copy of the whole ventral side of the body made by sandstone or only the part of it. Usually trace platforms are arranged in chains and orientated in one distinct direction. In spite of some superficial similarity, the fossils are neither body remains nor traces of post-mortem compression. The hypothesis of trace formation proposed suggests that the feeding strategy of Proarticulata was different from any feeding behavior known in large Phanerozoic animals. All types of imprints are identified as belonging to the genus Epibaion Ivantsov, 2002. It is proposed that the Australian fossil Phyllozoon Jenkins et Gehling, 1978 is also a feeding trace of Proarticulata.     

Growth of Acanthamoeba castellanii and Hartmannella vermiformis on live, heat-killed and DTAF-stained bacterial prey

The growth responses of two species of amoeba were evaluated in the presence of live, heat-killed and heat-killed/5-(4,6-dichlorotriazin-2-yl) aminofluorescein (DTAF)-stained cells of Escherichia coli, Pseudomonas aeruginosa, Klebsiella aerogenes, Klebsiella ozaenae and Staphylococcus aureus. The specific growth rates of both species were significantly higher with live bacterial prey, the only exception being Hartmannella vermiformis feeding on S. aureus, for which growth rates were equivalent on all prey states. There was no significant difference between growth rates, yield or ingestion rates of amoebae feeding on heat-killed or heat-killed/stained bacterial cells, suggesting that it was the heat-killing process that influenced the amoeba-bacteria interaction. Pretreatment of prey cells had a greater influence on amoebic processing of Gram-negative bacteria compared with the Gram-positive bacterium, which appeared to be as a result of the former cells being more difficult to digest and/or losing their ability to deter amoebic ingestion. These antipredatory mechanisms included microcolony formation in P. aeruginosa, toxin production in K. ozaenae, and the presence of an intact capsule in K. aerogenes. E. coli and S. aureus did not appear to possess an antipredator mechanism, although intact cells of the S. aureus were observed in faecal pellets, suggesting that any antipredatory mechanism was occurring at the digestion stage.     

Feeding live prey to zoo animals: response of zoo visitors in Switzerland

In summer 2007, with the help of a written questionnaire, the attitudes of more than 400 visitors to the zoological garden of Zurich, Switzerland, toward the idea of feeding live insects to lizards, live fish to otters, and live rabbits to tigers were investigated. The majority of Swiss zoo visitors agreed with the idea of feeding live prey (invertebrates and vertebrates) to zoo animals, both off‐ and on‐exhibit, except in the case of feeding live rabbits to tigers on‐exhibit. Women and frequent visitors of the zoo disagreed more often with the on‐exhibit feeding of live rabbits to tigers. Study participants with a higher level of education were more likely to agree with the idea of feeding live invertebrates and vertebrates to zoo animals off‐exhibit. In comparison to an earlier study undertaken in Scotland, zoo visitors in Switzerland were more often in favor of the live feeding of vertebrates. Feeding live prey can counter the loss of hunting skills of carnivores and improve the animals' well‐being. However, feeding enrichments have to strike a balance between optimal living conditions of animals and the quality of visitor experience. Our results show that such a balance can be found, especially when live feeding of mammals is carried out off‐exhibit. A good interpretation of food enrichment might help zoos to win more support for the issue, and for re‐introduction programs and conservation. Zoo Biol 29:344–350, 2010. © 2009 Wiley‐Liss, Inc.     

Some have it all: multicellularity,magnetotaxis and photokinesis in one bacterium

Bacteria developed many different ways to orient themselves in the environment. Magnetoreception with following motility along Earth's magnetic field lines and photoreception with subsequent positive or negative phototaxis allow bacteria to optimally position themselves for survival and growth. Some bacteria show both magnetotactic and photoresponsive behaviour and additionally live in a multicellular organism adding another layer of complexity. A novel study by Qian and colleagues visualized different species of multicellular magnetotactic bacteria and shed light on their reproductive as well as photoresponsive behaviour. This study paves the way towards understanding the evolutionary advantage of multicellular lifestyle of prokaryotes.     

New ideas on the origin of bilateral animals

Comparative anatomy and embryology provide impressive evidence that the ventral side of all Bilateria (except Chordata) originates from the blastoporal surface, while the mouth and anus develop, respectively, from the anterior and posterior extremities of an elongated blastopore. From the point of view of paleontology, some Vendian multicellular animals represent transitional forms between Radiata and Bilateria. Vendian Bilateria are metameric organisms with a symmetrical or asymmetrical arrangement of segments; they can be considered as bilaterally symmetrical coelenterates crawling on the oral surface. In the recent Cnidaria, homologues of the genes “Brachyury,” “goosecoid” and “fork head” are expressed around the mouth. In the recent Bilateria these genes are expressed along the elongated blastopore and around the mouth and anus. These data corroborate the validity of the idea of amphistomy and the homology between the ventral surface in Bilateria and oral disk in coelenterates. It is supposed that the ancestors of Bilateria were crawling on the oral surface (=ventral side) and gave rise to both Fanerozoic Cnidaria and triploblastic Bilateria. This allows us to suggest the origin of Bilateria from Vendian bilaterally symmetrical coelenterates with numerous metameric pockets of the gastral cavity. Such ancestors gave rise to both Cnidaria and Bilateria. Apparently the primary Bilateria were complicated organisms having a coelom and segmentation, which allows us to explain the great diversity of highly organized organisms (arthropods, mollusks, and others) in the Cambrian era. An idea is proposed that Ctenophora are the only group of recent Eumetazoa that retain primary axial symmetry.     

Experimental identification and in silico prediction of bacterivory in green algae

While algal phago-mixotrophs play a major role in aquatic microbial food webs, their diversity remains poorly understood. Recent studies have indicated several species of prasinophytes, early diverging green algae, to be able to consume bacteria for nutrition. To further explore the occurrence of phago-mixotrophy in green algae, we conducted feeding experiments with live fluorescently labeled bacteria stained with CellTracker Green CMFDA, heat-killed bacteria stained with 5-(4,6-dichlorotriazin-2-yl) aminofluorescein (DTAF), and magnetic beads. Feeding was detected via microscopy and/or flow cytometry in five strains of prasinophytes when provided with live bacteria: Pterosperma cristatum NIES626, Pyramimonas parkeae CCMP726, Pyramimonas parkeae NIES254, Nephroselmis pyriformis RCC618, and Dolichomastix tenuilepis CCMP3274. No feeding was detected when heat-killed bacteria or magnetic beads were provided, suggesting a strong preference for live prey in the strains tested. In parallel to experimental assays, green algal bacterivory was investigated using a gene-based prediction model. The predictions agreed with the experimental results and suggested bacterivory potential in additional green algae. Our observations underline the likelihood of widespread occurrence of phago-mixotrophy among green algae, while additionally highlighting potential biases introduced when using prey proxy to evaluate bacterial ingestion by algal cells.Subject terms: Microbial ecology, Cellular microbiology     

Attitude of zoo visitors to the idea of feeding live prey to zoo animals

Two hundred UK zoo visitors were asked about their attitudes regarding the feeding of live prey to zoo animals. All visitors agreed with live insects being fed to lizards, providing it was done off-exhibit, and only 4% objected if done on-exhibit. Seventy-two percent of visitors agreed with live fish being fed to penguins on-exhibit and 84.5% agreed to feeding live fish off-exhibit. However, only 32% agreed to a live rabbit being fed to a cheetah on exhibit, whereas 62.5% agreed to this if done off-exhibit. In general we found female interviewees more likely to object to the feeding of live vertebrate prey. Comments volunteered by interviewees suggested that they agreed with feeding live vertebrate prey because ‘it is natural’. If they objected, it was because ‘it would upset them or their children’. Zoo Biol 16:343–347, 1997. © 1997 Wiley-Liss, Inc.     

Changes in the communities of Paleozoic brachiopods due to their development of their filtering system

Onward changes in the communities of Paleozoic articulated brachiopods were mainly connected with the improvement of the function of their filter feeding system, which is responsible for the feeding of animals. Three major routes of improvement are known: (1) feeding using a primitive lophophore and specialized mantle (orders Strophomenida, Chonetida, and Productida); (2) increased complexity and enlargement of the spirolophe and the appearance of the spiral brachidium (orders Atrypida, Spiriferida, and Athyridida); (3) development of the protective structures preventing ingestible particles into the inner cavity of the shell (order Rhynchonellida). The most effective was the third variant that allowed rhynchonellids, which appeared in the Ordovician, to live up to recently and survive after two largest extinctions in the history of the group development: in the Late Devonian and at the Permian-Triassic boundary.     

Are late Proterozoic carbonaceous megafossils metaphytic algae or bacteria?

Pre-Phanerozoic carbonaceous megafossils are generally considered to be the remains of metaphytic algae. While these fossils are not particularly common, they are significant for the understanding on the global evolutionary level of the pre-Phanerozoic biota. Ribbon-shaped vendotaenids were interpreted as brown algae and represent the youngest, most common and geographically most widespread Precambrian carbonaceous megafossils. It now appears that they may be better understood as abandoned giant sheaths of sulfide oxidizing organotrophic bacteria related to the Modern Thioptoca among the Beggiatoaceae. □ Thallophyta, algae, methaphytes, Vendotaenidae, late Proterozoic, Precambrian, Vendian, bacteria.     

Facies distribution patterns of some marine benthic faunas in early paleozoic platform environments

Worldwide Late Cambrian—Silurian lithofacies patterns indicate that the platforms of that time were sites of accumulation of two essentially different rocks suites: the platform carbonate rocks and the platform terrigenous rocks. Most of the platform rocks accumulated as sediments in shallow marine environments similar to those of the present but far more widely spread.Present-day marine benthic faunas are distributed in depth zones which are primarily controlled by temperature. Faunas tend to occur in substrate-related discrete clusters (communities) within each life zone; similar substrates in different depth zones commonly have different faunal associations. Individual phyletic stocks may encounter environmental optimum or near-optimum conditions in certain areas, that commonly are revealed by an abundance of species and individuals within species in each stock. Environmental optimum conditions depend upon availability of food that may be utilized, modes of feeding of the animals present, water motion, and substrate, among other factors. Organisms in past seas were distributed in patterns similar to those of the present.Carbonate platforms were particularly widespread during the latest Cambrian—Early Ordovician. Intertidal environments spread widely across those platforms during that time and characteristic faunal associations developed in them. Saukiid and related tribolites dominated latest Cambrian carbonate platform intertidal faunas. The Early Ordovician carbonate platform intertidal was dominated by archeogastropod-nautiloid cephalopod faunas. These animals were joined by tabulate corals and certain brachiopods during the latter part of the Ordovician and Silurian as prominent faunal elements in the carbonate platform intertidal—shallow subtidal. Cruziana and related trace fossils, bivalves, and certain tribolites (notably homalonotids and dalmanitids) dominated most terrigenous platform intertidal—shallow subtidal faunas of the Ordovician and Silurian.Articulate brachiopods (primarily orthoids, strophomenoids, and rhynchonelloids) appear to have been relatively prominent during the Early Ordovician in shallow subtidal environments on both carbonate and terrigenous platforms and to have spread down the bathymetric gradient into increasingly deeper subtidal areas of both platforms during the latter part of the Ordovician. Tribolites dominated faunas in relatively moderate to deep subtidal environments on both platforms during the early part of the Ordovician. They were gradually replaced by brachiopods in first the shallower, and later the deeper subtidal as dominant members of the faunas. Brachiopods (primarily pentameroids and spiriferoids) dominated nearly all Silurian warm-water subtidal environments from the shallow subtidal to the edges of the platforms.Platform uplifts in the Middle Ordovician and glacio-eustatic sea-level fluctuations in the Late Ordovician caused environmental changes across the platforms that were accompanied by marked replacements among marine benthic faunas in all environments. The distribution of Ordovician carbonate platforms and glacial deposits suggests that an Ordovician polar region may have been close to present-day equatorial Africa and that Ordovician warm temperate-tropical regions lay close to the present-day North Pole.     

Experience and social environment influence the ability of young brown trout to forage on live novel prey

Efficient feeding is crucial for the growth, survival and reproductive success of most animals. In artificial-rearing environments, however, animals are deprived of many stimuli normally experienced in the wild, which may alter feeding behaviour, and thus influence their survival and reproductive success upon release in nature. In a laboratory experiment, we investigated the effect of hatchery rearing on the ability of brown trout, Salmo trutta, to capture and consume a novel live prey item. Hatchery-reared and wild-caught trout, originating from the same river, were fed single black crickets, either in isolation or in visual and olfactory contact with another hatchery-reared or wild-caught fish. Total consumption, time to first bite and feeding efficiency were monitored. Wild-caught trout ate more, were quicker to attack, and consumed attacked prey more efficiently than hatchery-reared fish. Food consumption and efficiency increased in both wild and hatchery-reared trout during the experiment. We propose that the differences in feeding ability between wild-caught and hatchery-reared brown trout were mainly due to differences in previous experience of feeding on live prey. Wild-caught trout tended to eat more and sooner when in visual contact with another fish than when in isolation. This trend was not seen for the hatchery-reared fish, which may be due to environmental differences between the hatchery and the natural stream. The initial inability of hatchery-reared fish to forage on live prey may reduce their success when released in the wild, especially when in competition with resident wild fish. Copyright 2001 The Association for the Study of Animal Behaviour.     

The effect of level of feeding, genetic merit, body condition score and age on biological parameters of a mammary gland model

An evolutionary algorithm was applied to a mechanistic model of the mammary gland to find the parameter values that minimised the difference between predicted and actual lactation curves of milk yields in New Zealand Jersey cattle managed at different feeding levels. The effect of feeding level, genetic merit, body condition score at parturition and age on total lactation yields of milk, fat and protein, days in milk, live weight and evolutionary algorithm derived mammary gland parameters was then determined using a multiple regression model. The mechanistic model of the mammary gland was able to fit lactation curves that corresponded to actual lactation curves with a high degree of accuracy. The senescence rate of quiescent (inactive) alveoli was highest at the very low feeding level. The active alveoli population at peak lactation was highest at very low feeding levels, but lower nutritional status at this feeding level prevented high milk yields from being achieved. Genetic merit had a significant linear effect on the active alveoli population at peak and mid to late lactation, with higher values in animals, which had higher breeding values for milk yields. A type of genetic merit × feeding level scaling effect was observed for total yields of milk and fat, and total number of alveoli produced from conception until the end of lactation with the benefits of increases in genetic merit being greater at high feeding levels. A genetic merit × age scaling effect was observed for total lactation protein yields. Initial rates of differentiation of progenitor cells declined with age. Production levels of alveoli from conception to the end of lactation were lowest in 5- to 8-year-old animals; however, in these older animals, quiescent alveoli were reactivated more frequently. The active alveoli population at peak lactation and rates of active alveoli proceeding to quiescence were highest in animals of intermediate body condition scores of 4.0 to 5.0. The results illustrate the potential uses of a mechanistic model of the mammary gland to fit a lactation curve and to quantify the effects of feeding level, genetic merit, body condition score, and age on mammary gland dynamics throughout lactation.     

繁茂膜海绵细胞内微生物多样性的研究

采用海绵组织离散、细胞分离的方法,对繁茂膜海绵细胞进行纯化、胞内微生物DNA提取,构建了繁茂膜海绵细胞内微生物的16SrDNA克隆,对其遗传多样性进行了分析,发现海绵细胞内微生物16SrDNA序列主要归类于紫硫细菌门(Proteobacteria)中的α-亚门、γ-亚门和浮霉菌门(Planctomycetes)等类群。与研磨直接提取海绵组织DNA所得海绵组织中总微生物多样性相比,海绵细胞内存在丰富的浮霉菌(23%),说明浮霉菌主要存在于海绵细胞胞内。     

Colonization of substrates: Vendian sedentary benthos

Studies of fossils sampled from a single fossiliferous layer (monotopic series) and a summary of previous data on taphonomy and morphology of Vendian macroorganisms suggest that most strategies of attachment of sedentary benthos were formed in the Vendian. These included: (1) free living with possible organic gluing; (2) fixation on the substrate using sucker-like structures and various incrustations; (3) fixation of the basal parts by shallow submergence in the sediment; (4) anchoring into the sediment with discoidal and rhizoid-like holdfasts; and (5) partial submergence and infaunal lifestyle. The most widespread fixation in the Vendian was the attachment by discoid organs, which can be interpreted as symbiotrophic structures. Symbiotrophy in Vendian organisms submerged in the anoxic sediment can apparently be supported by indirect evidence: structural diversity of basal organs, their complex morphology, large area of contact with substrate, unlimited isometric growth, predominant fossilization of attachment discs; inconsistent systematization of organisms.     

The Microflora and Concentrations of Volatile Fatty Acids in The Rumen of Cattle Fed on Single Component Rations

The composition of the rumen microflora and the volatile fatty acids were examined in cattle free-grazing on grass or stall-fed on hay, grass pellets, oats or dried beet pulp with molasses. Total and viable counts of anaerobic bacteria were highest on the grass feeding, but viable counts as a percentage of total counts were highest when oats or beet pulp with molasses were fed. Counts of cellulolytic bacteria were lowest on these latter 2 diets, and highest on grass or grass pellet diets. Studies of the anaerobic flora showed that the composition in animals fed on grass pellets resembled more that found in animals free-grazing on grass than in those fed on hay. Counts of aerotolerant bacteria were only a small percentage of the total count, but were highest on the hay diet. On this latter diet and on grass-feeding the streptococci (identified as Streptococcus bovis) were predominant, but contrary to expectation, streptococci were found only in small numbers on the oats diet, where coryneform rods were the major type present. Although a period of 4–6 weeks was allowed for the animals to adapt to the feeds, the 2 periods of feeding on oats and dried beet pulp with molasses markedly affected the composition of the rumen flora in the subsequent periods of feeding grass pellets and hay. Ruinen volatile fatty acid analysis showed a propionogenic effect of oats and the highest percentage of butyric acid when beet pulp with molasses was fed. The expected propionogenic effect of grass pellets was not observed.