scholarly journals Dramatic dietary shift maintains sequestered toxins in chemically defended snakes

2020 ◽  
Vol 117 (11) ◽  
pp. 5964-5969 ◽  
Author(s):  
Tatsuya Yoshida ◽  
Rinako Ujiie ◽  
Alan H. Savitzky ◽  
Teppei Jono ◽  
Takato Inoue ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gut Contents ◽  
Dorsal Skin ◽  
Dietary Shift ◽  
Anuran Amphibians ◽  
Feeding Experiments ◽  
Dramatic Shift ◽  
Nuchal Glands ◽  
Group Species ◽  
Preference Tests

Unlike other snakes, most species ofRhabdophispossess glands in their dorsal skin, sometimes limited to the neck, known as nucho-dorsal and nuchal glands, respectively. Those glands contain powerful cardiotonic steroids known as bufadienolides, which can be deployed as a defense against predators. Bufadienolides otherwise occur only in toads (Bufonidae) and some fireflies (Lampyrinae), which are known or believed to synthesize the toxins. The ancestral diet ofRhabdophisconsists of anuran amphibians, and we have shown previously that the bufadienolide toxins of frog-eating species are sequestered from toads consumed as prey. However, one derived clade, theRhabdophis nuchalisGroup, has shifted its primary diet from frogs to earthworms. Here we confirm that the worm-eating snakes possess bufadienolides in their nucho-dorsal glands, although the worms themselves lack such toxins. In addition, we show that the bufadienolides ofR. nuchalisGroup species are obtained primarily from fireflies. Although few snakes feed on insects, we document through feeding experiments, chemosensory preference tests, and gut contents that lampyrine firefly larvae are regularly consumed by these snakes. Furthermore, members of theR. nuchalisGroup contain compounds that resemble the distinctive bufadienolides of fireflies, but not those of toads, in stereochemistry, glycosylation, acetylation, and molecular weight. Thus, the evolutionary shift in primary prey among members of theR. nuchalisGroup has been accompanied by a dramatic shift in the source of the species’ sequestered defensive toxins.

The structure and distribution of proteochondroitin sulphate during the formation of chick embryo feather germs

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 501-512 ◽  
Author(s):  
KUNIO KITAMURA
Keyword(s):  
Molecular Weight ◽  
Chick Embryo ◽  
Basement Membrane ◽  
The Other ◽  
Dorsal Skin ◽  
Superficial Dermis ◽  
Dermal Cells ◽  
Asymmetrically Distributed ◽  
Slow Turnover ◽  
Feather Buds

The dorsal skin of the chick embryo, in which feather germ forms, was found to synthesize two proteochondroitin sulphates, PCS-I and PCS-II and a proteoheparan sulphate, PHS. A monoclonal antibody (I3B9) was prepared against PCS-I, a higher molecular weight proteochondroitin sulphate. Distribution of PCS-I was immunohistochemically studied using I3B9. PCS-I was found in the epidermis, basement membrane and superficial dermis prior to formation of feather rudiments. As the feather rudiments formed, PCS-I was noted in a condensed area of dermal cells and in the basement membrane, while PCS-I decreased remarkably in the epidermal placode. The formation of feather buds resulted in a decrease in PCS-I in the region of dermal condensation and the basement membrane situated above this region. PCS-I was asymmetrically distributed in the feather filaments. The turnover of proteochondroitin sulphate was studied using autoradiography of [35S]sulphate. Proteochondroitin sulphate in the basement membrane and condensed dermis of the feather rudiments showed very slow turnover. On the other hand, the outgrowth of feather buds caused rapid turnover of proteochondroitin sulphate in the region of dermal condensation and basement membrane situated above this region. The mechanism for the uneven distribution of PCS-I during feather germ formation is discussed.

scholarly journals Diets and Seasonal Ingestion Rates of Aurelia coerulea (Cnidaria: Scyphozoa) Polyps by in situ Feeding Experiments in Jiaozhou Bay, China

2021 ◽  
Vol 8 ◽  
Author(s):  
Wang Pengpeng ◽  
Zhang Fang ◽  
Guo Dongjie ◽  
Sun Song
Keyword(s):  
Prey Capture ◽  
Prey Availability ◽  
Ingestion Rate ◽  
Jiaozhou Bay ◽  
Gut Contents ◽  
Natural Diet ◽  
Ingestion Rates ◽  
Aurelia Coerulea ◽  
Feeding Experiments

The benthic scyphopolyp population is an important stage in the scyphozoan lifecycle. Nevertheless, few studies have detailed the natural feeding and quantified the energy flux of polyps based on field research. To better understand the scyphopolyp natural diet and seasonal variation patterns in the ingestion rate, in situ feeding experiments were conducted on Aurelia coerulea polyps in Jiaozhou Bay, China from August 2018 to April 2019. The diet of A. coerulea polyps was determined by gut content analysis. Digestion rates were also measured. Ingestion rates, based on the gut contents and digestion rates, were assessed monthly. Copepods, copepod nauplii, and ciliates were identified in the guts of A. coerulea polyps. Copepods with the bulk of total prey intake in number are an important source of nutrition for A. coerulea polyps in Jiaozhou Bay. Prey capture of A. coerulea polyps (prey polyp–1) varied among months, and was highly dependent upon the abundance of planktonic prey in the habitat. Copepods and copepod nauplii were digested more rapidly as temperature increased. Carbon weight-specific ingestion rate exhibited an obvious seasonal change, with the mean value of 0.13 ± 0.12 μg C μg C–1 d–1. More rapid digestion of prey at higher temperatures and larger prey availability would cause a higher ingestion rate in polyps. Scyphopolyps are widely distributed predators in littoral ecosystems and they may play an important role in plankton–benthos coupling by transferring energy from the water column to the benthos. Massive scyphopolyps blooms may influence pelagic ecosystems.

scholarly journals Reproduction and feeding habits of the River Catfish Eutropiichthys vacha (Hamilton, 1822) (Siluriformes, Schilbidae) in an impacted habitat: Kotri hydrodam, River Indus, Pakistan

Our Nature ◽  
2013 ◽  
Vol 10 (1) ◽  
pp. 269-280 ◽  
Author(s):  
Anila Naz Soomro ◽  
Wazir Ali Baloch ◽  
Sayed Iftikhar Hussain Jafri ◽  
Ghulam Hussain Burdi ◽  
Bernerd Fulanda
Keyword(s):  
Feeding Habits ◽  
Gonadal Development ◽  
Temporal Variations ◽  
Cold Season ◽  
Male Dominance ◽  
Minimum Size ◽  
Gut Contents ◽  
Feeding Intensity ◽  
Dietary Shift ◽  
River Indus

Reproduction and feeding habits of Eutropiichthys vacha were studied in Kotri hydrodam, a man-made and human impacted stretch of the Indus River, Pakistan during 2005-2006. A total 303 specimens were sampled and analyzed for maturity stages and gonadal development and food and feeding habits assessed from gut contents. Results showed male dominance over females: sex ratio 1.16:1.0. Minimum size at sexual maturity was 13.9 cm total length (TL). Mean fecundity ranged 1.38x104 to 2.17 x 105. Gonado-somatic index (GSI) was 0.1-2.5 and 0.3-6.5 for males and females, respectively. Highest GSIs were recorded in April. We observe an ontogenic dietary shift in E. vacha: young are omnivorous with insects dominating diet while adults are omni-piscivores with Puntius ticto accounting for 35.4% of species. Other species were Colisa spp., juveniles of Channa spp. and some cyprinids. Feeding intensities were lowest in April at peak of spawning. The intensities increase rapidly after spawning indicating voracious feeding in E. vacha. Feeding intensities in adults are low during the cold season. These results provide for assessment of spatial-temporal variations in feeding intensity in E. vacha while GaSI and diet composition reveal information on environmental shifts and ecosystem fluctuations in the impacted habitats of the River Indus for sound fisheries management.DOI: http://dx.doi.org/10.3126/on.v10i1.7795

scholarly journals Selective predation by Neomysis mercedis in Lake Washington

2017 ◽  
Author(s):  
Paul A. Murtaugh
Keyword(s):  
Large Population ◽  
Gut Contents ◽  
Selective Predation ◽  
Feeding Experiments ◽  
Effective Predator ◽  
Lake Washington

Ahstroct Feeding experiments and examination of gut contents show that Neomysis mercedis is an effective predator on zooplankton in Lake Washington. Daphnia is consistently preferred to other prey; Diaptomus and Cyclops copepodids and nauplii are always underrepresented in mysid diets. This pattern of selectivity is consistent with the hypothesis that a large population of Neomysis formerly excluded Daphnia from the lake.

Resource partitioning among five sympatric species of freshwater turtles from the wet–dry tropics of northern Australia

2017 ◽  
Vol 44 (3) ◽  
pp. 219 ◽  
Author(s):  
Michael A. Welsh ◽  
J. Sean Doody ◽  
Arthur Georges
Keyword(s):  
Resource Partitioning ◽  
Niche Overlap ◽  
Sympatric Species ◽  
Dry Season ◽  
Gut Contents ◽  
Microhabitat Use ◽  
Freshwater Turtles ◽  
Northern Australia ◽  
Dietary Shift ◽  
Dry Tropics

Context Resource partitioning of diet and microhabitat was examined for five sympatric species of freshwater turtles in the Daly River in the northern end of Northern Territory (Top End) in Australia. The Daly River supports a high diversity of freshwater turtles, making it the ideal place to study a freshwater turtle community. Aims To determine the dry-season diet and microhabitat use of Carettochelys insculpta, Elseya dentata, Chelodina oblonga, Emydura victoriae and Emydura subglobosa worrelli and examine intraspecific and interspecific niche overlap and ontogenetic dietary shift. Methods Gut contents were collected by stomach flushing, and microhabitat use was determined by recording where each turtle was first seen before capture. Diet and microhabitat use were compared using an index of relative importance. Niche overlap was measured with Horn’s overlap index. Key results Carettochelys insculpta is an opportunistic omnivore that feeds mostly on ribbonweed (Vallisneria spiralis) and aquatic snails. Elseya dentata is herbivorous, feeding primarily on aquatic algae. The diets of C. insculpta and E. dentata overlapped moderately, but the overall niche overlap was low because they occupied different microhabitats within the river. Chelodina oblonga fed very little, and may use the Daly River as a dry-season refuge. Emydura victoriae is molluscivorous, consuming more molluscs as it grows. This ontogenetic dietary shift was associated with megacephaly (extreme broadly expanded head that is too large to fit into the carapace) and expanded triturating surfaces. This specialisation allows adult E. victoriae to feed exclusively on molluscs and so their diet overlapped little with other species. Emydura subglobosa worrelli was omnivorous, consuming mostly freshwater sponge and apparently preferring more lentic water. Conclusions The freshwater turtles of the wet–dry tropics are usually reported as being heavily reliant on the seeds, fruits and leaves of riparian vegetation; however, the present study showed that the dry-season diet in perennial rivers is primarily of aquatic origin. Implications The study suggested that populations of C. insculpta, E. dentata and E. victoriae could be threatened by broad-scale development in northern Australia if there were substantive impacts on aquatic macrophytes and molluscs in the Daly River system.

scholarly journals The β-glucosidase in the gut contents of the snail Achatina achatina

1976 ◽  
Vol 157 (2) ◽  
pp. 381-387 ◽  
Author(s):  
G M Umezurike
Keyword(s):  
Molecular Weight ◽  
Heat Stability ◽  
Molecular Forms ◽  
Gut Contents ◽  
Ph Optimum ◽  
Optimum Ph ◽  
Michaelis Constants ◽  
Molecular Complexity ◽  
Beta Glucosidase ◽  
Digestive Glands

1. The enzyme beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) from the gut contents of active Achatina achatina exists in two molecular forms, beta-glucosidase C (mol.wt. about 82000) and D (mol.wt. about 41000). 2. Only the lower-molecular-weight species was found in the gut contents of aestivating snails or in extracts from their digestive glands and washed gut walls. 3. On re-activation of some aestivating snails, betion of ATP and Mg2+ to the isolated gut contents or to extracts from washed gut walls led to the formation of higher-molecular-weight forms of the enzyme, beta-glucosidase A (mol.wt. about 329000) and beta-glucosidase B (mol.wt. about 165000). 5. All these forms of the enzyme have similar pH optimum (pH 5.0-5.6). 6. The Michaelis constants (Km) and heat stability of the enzyme increased with increasing molecular complexity.

Interaction and coevolution of plants and arthropods during the Palaeozoic and Mesozoic

1992 ◽  
Vol 335 (1274) ◽  
pp. 129-165 ◽  
Keyword(s):  
Vascular Plant ◽  
Eating Behaviour ◽  
Chemical Defence ◽  
Gut Contents ◽  
Upper Carboniferous ◽  
Plant Fossils ◽  
Terrestrial Arthropods ◽  
Feeding Experiments ◽  
Fossil Evidence ◽  
Defence Strategies

Fossil evidence of terrestrial vascular plant life and terrestrial arthropods exists from the Silurian. Fossil evidence suggests progressive interaction between the two groups through the later Palaeozoic and Mesozoic. In this paper we present data, particularly from plant fossils, concerning several interactions: feeding, shelter, transport and reproduction. Evidence of arthropod feeding includes eaten leaves, borings in plant tissues, wound reaction and leaf mining as well as gut contents and coprolites from the arthropods themselves. We trace the changes in leaf eating behaviour from continuous marginal feeding, common in the Palaeozoic and early Mesozoic to the more abundant interrupted-marginal and non- marginal feeding behaviour on Cretaceous angiosperm leaves. This change may reflect the evolution of chemical defence strategies by the plants but may also reflect the evolution of different mouthpart design in new insect groups. Leaf mines and leaf galls, although known from the Upper Carboniferous, only become common in the Cretaceous, coinciding with the evolution of several new insect groups and plants. Wood boring is recorded, for the first time, from the Lower Carboniferous and becomes common from the Upper Carboniferous. Data from coprolites suggest that spore feeding preceded leaf feeding. Experiments using pteridophytes and living arthropods indicate that some spores remain viable after passing through the gut and hence this feeding habit may have also been advantageous to some early plants for propagule transport. We conclude that there is much evidence in the fossil record suggesting plant-arthropod interaction, but many more observations are required before detailed interpretations concerning coevolution can be made.

scholarly journals An endogeneous inhibitor of microsomal mixed-function oxidases in homogenates of the southern armyworm (Prodenia eridania)

1970 ◽  
Vol 116 (5) ◽  
pp. 781-789 ◽  
Author(s):  
R. I. Krieger ◽  
C. F. Wilkinson
Keyword(s):  
Molecular Weight ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Inhibitory Activity ◽  
Bovine Serum ◽  
Potent Inhibitor ◽  
Gut Contents ◽  
Microsomal Enzymes ◽  
Mixed Function Oxidases ◽  
Southern Armyworm

1. A potent inhibitor of microsomal mixed-function oxidation has been isolated from the gut contents of larvae of the southern armyworm (Prodenia eridania). 2. Progressive inhibition is associated with a soluble proteinase with a molecular weight of approx. 26000. 3. Although the proteolytic activity of the inhibitor can be reduced by phenylmethanesulphonyl fluoride and other reagents, these materials are only partially effective in protecting the microsomal enzymes. 4. Inhibitory activity is decreased in the presence of bovine serum albumin.

Ecological Feeding Analysis of South-Eastern Australian Scincids (Reptilia, Lacertilia)

1991 ◽  
Vol 39 (1) ◽  
pp. 9 ◽  
Author(s):  
GW Brown
Keyword(s):  
Body Size ◽  
Vertical Distribution ◽  
Food Selection ◽  
Gut Contents ◽  
Individual Species ◽  
Food Items ◽  
South Eastern ◽  
Eastern Australia ◽  
Group Species ◽  
South Eastern Australia

The gut contents of 936 skinks, representing 15 species resident in south-eastern Australia, were examined. Multicategorisation of food items reveals that a wide variety of plant and invertebrate material is ingested, the proportions and types of which appear to be dependent upon several criteria. All species investigated are opportunistic and widely foraging generalists, although important determinants of food selection appear to be the size of the lizard and its vertical distribution. When the diets of individual species are amalgamated according to suprageneric groups, certain dietary traits emerge. Egernia-group species, which are relatively large, are generally herbivorous, with the degree of herbivory correlated directly to body size. Smaller species of the Leiolopisma (Eugongylus) and Sphenomorphus groups mainly eat insects.

Predation and Competition

2020 ◽  
pp. 361-382
Author(s):  
Samuel M. Bashevkin ◽  
Steven G. Morgan
Keyword(s):  
Chemical Defenses ◽  
Gut Contents ◽  
Future Research ◽  
Review Of The Literature ◽  
Important Species ◽  
Trade Off ◽  
Interspecific Differences ◽  
Feeding Experiments ◽  
Commercially Important ◽  
Abundance And Distribution

Crustacean larvae are subject to predation by a diverse assemblage of invertebrate and vertebrate predators. These predators can find larval prey through visual, tactile, or chemical means and then capture larvae with feeding currents, grasping appendages, suction, or filtering sieves. In response to this predation, crustacean larvae have evolved extensive morphological defenses such as long spines and hard chitinous carapaces. They also exhibit sophisticated behaviors, including extensive vertical and horizontal migrations to avoid encountering predators, rapid darting to evade attacks by nearby predators, and strong swimming to escape after an attack by a predator. Chemical defenses have not yet been documented in crustacean larvae. Interspecific differences in defensive capabilities can be profound, including crab zoeae with spines zero to seven times their body length, and copepod nauplii with dichotomous swimming behaviors that trade off detectability by predators with escape ability. Our review of the literature on predator gut contents and lab feeding experiments found that crustacean larvae are consumed by a vast diversity of predators of all feeding types. These include gray whales, fishes, ascidians, bivalves, octopus larvae, cnidarians, insects, and numerous other crustaceans. Crustacean larvae are important components of many predators’ diets, and the primary food for others, including larvae of commercially important species such as cod. Future research on chemical defenses and phenotypic plasticity are needed to fill gaps in our knowledge of crustacean larval defenses. The predatory threats faced by crustacean larvae and their defensive adaptations have important implications for our understanding of the evolution of larval forms in Crustacea and the factors determining crustacean abundance and distribution.

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