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15 recordsLinked to original sources
PubMed2024

Comparative transcriptomics of Venus flytrap (Dionaea muscipula) across stages of prey capture and digestion.

The Venus flytrap, Dionaea muscipula, is perhaps the world's best-known botanical carnivore. The act of prey capture and digestion along with its rapidly closing, charismatic traps make this species a compelling model for studying the evolution and fundamental biology of carnivorous plants. There is a growing body of research on the genome, transcriptome, and digestome of Dionaea muscipula, but surprisingly limited information on changes in trap transcript abundance over time since feeding. Here we present the results of a comparative transcriptomics project exploring the transcriptomic changes across seven timepoints in a 72-hour time series of prey digestion and three timepoints directly comparing triggered traps with and without prey items. We document a dynamic response to prey capture including changes in abundance of transcripts with Gene Ontology (GO) annotations related to digestion and nutrient uptake. Comparisons of traps with and without prey documented 174 significantly differentially expressed genes at 1 hour after triggering and 151 genes with significantly different abundances at 24 hours. Approximately 50% of annotated protein-coding genes in Venus flytrap genome exhibit change (10041 of 21135) in transcript abundance following prey capture. Whereas peak abundance for most of these genes was observed within 3 hours, an expression cluster of 3009 genes exhibited continuously increasing abundance over the 72-hour sampling period, and transcript for these genes with GO annotation terms including both catabolism and nutrient transport may continue to accumulate beyond 72 hours.

Droseraceae↗
PubMed2024

The evolution of cnidarian stinging cells supports a Precambrian radiation of animal predators.

Cnidarians-the phylum including sea anemones, corals, jellyfish, and hydroids-are one of the oldest groups of predatory animals. Nearly all cnidarians are carnivores that use stinging cells called cnidocytes to ensnare and/or envenom their prey. However, there is considerable diversity in cnidocyte form and function. Tracing the evolutionary history of cnidocytes may therefore provide a proxy for early animal feeding strategies. In this study, we generated a time-calibrated molecular clock of cnidarians and performed ancestral state reconstruction on 12 cnidocyte types to test the hypothesis that the original cnidocyte was involved in prey capture. We conclude that the first cnidarians had only the simplest and least specialized cnidocyte type (the isorhiza) which was just as likely to be used for adhesion and/or defense as the capture of prey. A rapid diversification of specialized cnidocytes occurred through the Ediacaran (~654-574 million years ago), with major subgroups developing unique sets of cnidocytes to match their distinct feeding styles. These results are robust to changes in the molecular clock model, and are consistent with growing evidence for an Ediacaran diversification of animals. Our work also provides insight into the evolution of this complex cell type, suggesting that convergence of forms is rare, with the mastigophore being an interesting counterexample.

Animals↗
PubMed1979

The effect of luminance upon the distribution and behavior of the Eleotrid fish Gobiomorus dormitor, and its prey.

Gobiomorus dormitor success in capturing prey, cichlids, poeciliids and atherinids, is correlated with low luminance. Both prey and predator populations inhabiting rocky areas in Lake Jiloa, Nicaragua shift to deeper water during the dry season when luminance is greater. Predator and prey populations are also deeper over bright sandy areas than over rocks. Predators, during the middle of the day, attack prey significantly less in water above 3 m than in water between 3-12 m, but there is a significant increase in the number of attacks occurring above 3 m at twilight. The predator becomes more active, and the prey disappear into holes at twilight. These data suggest that conclusions concerning the importance of light in structuring the community and behavior of marine fishes can be generalized to tropical freshwater systems.

Animals↗
PubMed2024

Foraging mechanisms in excavate flagellates shed light on the functional ecology of early eukaryotes.

The phagotrophic flagellates described as "typical excavates" have been hypothesized to be morphologically similar to the Last Eukaryotic Common Ancestor and understanding the functional ecology of excavates may therefore help shed light on the ecology of these early eukaryotes. Typical excavates are characterized by a posterior flagellum equipped with a vane that beats in a ventral groove. Here, we combined flow visualization and observations of prey capture in representatives of the three clades of excavates with computational fluid dynamic modeling, to understand the functional significance of this cell architecture. We record substantial differences amongst species in the orientation of the vane and the beat plane of the posterior flagellum. Clearance rate magnitudes estimated from flow visualization and modeling are both like that of other similarly sized flagellates. The interaction between a vaned flagellum beating in a confinement is modeled to produce a very efficient feeding current at low energy costs, irrespective of the beat plane and vane orientation and of all other morphological variations. Given this predicted uniformity of function, we suggest that the foraging systems of typical excavates studied here may be good proxies to understand those potentially used by our distant ancestors more than 1 billion years ago.

Flagella↗
PubMed1978

Development of the compound eyes of dragonflies (Odonata). III. Adult compound eyes.

The distribution of ommatidial diameters and interommatidial angles, as determined by measuring the angles between the optic axes of adjacent ommatidia, are mapped across the surface of the compound eyes of a variety of species selected for different adult behaviors, developmental histories, and taxonomic positions. The size of the visual fields, prey capture foveas, foveas composed of large dorsal ommatidia, and other specializations in the numbers of ommatidia that view various directions in the visual field are discussed in relation to adult behavior. Advanced species have less resemblance between their larval and adult eyes than primitive species. In contrast to their larvae, adults increase the monocular resolution of each eye at the expense of binocular vision. Most species have foveas which view in approximately the anterior direction, instead of in a region of binocular overlap, and many species have foveal bands which view along the horizon. Some advanced perching species, which approach their prey and other odonates from below, have an additional vertical foveal band that views along a vertical plane from the anterior direction to a more dorsal direction. The most unusual foveal band is seen in active flying species. The large dorsal ommatidia of the migratory Anax junius, which cover approximately one third of the eye surface, view a narrow region of the visual field that extends along a plane from the most lateral direction of one eye to a dorsal direction, and continues without interruption to the most lateral direction of the other eye.

Animals↗
PubMed2026

Multifunctional lysozymes from the assassin bug Sycanus bifidus: Insecticidal proteins with anticoagulant and melanization inhibition properties.

BACKGROUND: Predatory hemipterans deploy complex venom cocktails to immobilize preys, yet the specific roles of many individual venom components remain poorly understood. RESULTS: Four lysozyme genes were identified from the genome of the predatory assassin bug Sycanus bifidus (Hemiptera: Reduviidae), comprising one i-type (SbLyzi) and three c-type lysozyme genes (SbLyzc1-3). Transcriptomic and quantitative (q)PCR analyses revealed that these lysozymes were expressed at different levels in various venom glands. Of them, SbLyzc1-3 with signal peptides displayed significant transcriptions in the venom glands, implicating these lysozymes as venom constituents. Functional assays found that SbLyzc1 and SbLyzc2 showed antibacterial activity against Pseudomonas aeruginosa and Enterococcus faecalis. Three lysozymes (SbLyzi, SbLyzc1 and SbLyzc3) suppressed thrombin-induced fibrin clot formation, indicating anticoagulant activity, with SbLyzc1 exhibiting the greatest potency [half-maximal inhibitory concentration (IC50) = 0.036 ± 0.003 μg μL-1]. SbLyzi and SbLyzc1 inhibited phenoloxidase activity in the hemolymph of the yellow mealworm Tenebrio molitor pupae, thereby suppressing its hemolymph melanization, with maximal inhibition rates of 78.4% and 74.3%, respectively. All four lysozymes exhibited insecticidal effects, causing >80% mortality in yellow mealworm pupae following injection of 6 μg per individual, with SbLyzc1 showing the highest insecticidal potency [half-maximal lethal dose (LD50) = 4.25 ± 0.51 μg g-1]. CONCLUSION: These findings demonstrate that lysozymes from S. bifidus possess multifunctional biological activities and SbLyzc1-3 act as significant venom components involved in capturing prey, providing new insights into the functional diversity of lysozymes in predatory bugs and their potential application in biological control strategies. © 2026 Society of Chemical Industry.

Animals↗
PubMed2026

Sex- and development-specific transcriptomic profiling of venom and silk genes in the wolf spider Pardosa astrigera provides insights into ecological adaptation and predatory strategies.

Spider venom and silk glands are two major secretory systems that contribute to prey capture, defense, and reproduction, but their sex- and development-specific molecular regulation in wandering wolf spiders remains poorly understood. Here, the transcriptome of Pardosa astrigera, an important agricultural natural enemy in China, revealed significant sex- and development-associated molecular differentiation among adult females, adult males, and spiderlings. A total of 100,025 unigenes were obtained, of which 23,852 were functionally annotated, providing a comprehensive transcriptomic resource for this species. Differential expression patterns showed marked variation among groups, with 531, 1792, and 832 DEGs detected in PAF vs PAS, PAM vs PAS, and PAF vs PAM, respectively. These genes were mainly associated with metabolic, oxidation-reduction, cuticle development, MAPK signaling, and lysosome pathways. Fifteen co-expression modules revealed distinct expression patterns. The turquoise, pink, yellow, and red modules were development-related, whereas the blue module was male-biased. Venom- and spidroin-related genes were distributed across multiple modules, suggesting coordinated regulation. Overall, 42 venom peptides, 21 venom proteins, and 11 spidroins were identified. Representative genes showed strongly biased expression, including spiderling-biased U3_Pp1a and U5_Pp1e, female-biased U4_Pp1a, and male-biased SMase D_108750 and PaTuSp_108466. These findings reveal sex- and development-biased expression patterns of venom- and silk-related candidate genes in P. astrigera and may provide molecular insights into ecological adaptation and predatory strategies in wandering wolf spiders.

Animals↗
PubMed2026

Skull morphology of the extinct Tasmanian tiger suggests unique biting style.

The recently extinct thylacine (Tasmanian tiger) was the largest modern marsupial predator. It is considered a classic example of evolutionary convergence due to striking similarities with placental canids (e.g., foxes and wolves), particularly in the skull, despite ~160 million years of evolutionary separation. However, we here present geometric and linear morphometric evidence that the thylacine's cranial form arises from a mosaic of traits not represented among canids or other living mammalian carnivores. Thylacines had disproportionately large heads, tall and gracile snouts with a flared canine region, and conspicuously large infraorbital foramina. Many of these traits suggest adaptations to fast, high-impact snapping behaviour in prey capture, as proposed for several living and extinct predatorial vertebrates with similar trait combinations. The thylacine's cranial function may therefore not be inferable from observation of living mammals. However, genomic progress presents new opportunities for future insights into the evolution and development of thylacine cranial adaptation.

Animals↗
PubMed1979

Target range-sensitive neurons in the auditory cortex of the mustache bat.

Echolocating bats determine distance to targets by the time delay between their emitted biosonar pulses and the returning echoes. By varying the delay between synthetic pulses and echoes in stimulus pairs at various repetition rates and durations, neurons have been found in the auditory cortex of the mustache bat (Pteronotus parnellii rubiginosus) which are sensitive to target range during the search, approach, and terminal phases of prey capture or landing. Two classes of range-sensitive neurons were found: (i) tracking neurons, whose best delay for response to an echo following the emitted pulse becomes shorter and narrower as the bat closes in on the target, and (ii) range-tuned neurons, whose best delay is constant, and which respond to the target only when it is within a certain narrow fixed range. Range-tuned neurons are specialized for processing echoes only during a particular period of the search, approach, or terminal phases of echolocation, and they provide support for a theory of ranging in bats that incorporates groups of neurons with a spectrum of preferred echo delays to detect target distance.

Action Potentials↗
PubMed1975

Fatal pox infection in a rough-legged hawk.

Natural pox infection occurred in a free-living rough-legged hawk (Buteo lagopus) in northeastern North Dakota. Gross, histological and electron microscopic findings were typical of pox infection, and characteristic lesions developed in red-tailed hawks (Buteo jamaicensis) but not in great horned owls (Bubo virginianus) following inoculation with case material. Death of the rough-legged hawk was attributed to starvation rsulting from inability to capture prey and to blood loss from foot lesions.

Animals↗
PubMed1979

A functional interpretation of the varanid dentition (Reptilia, Lacertilia, Varanidae).

A cinéradiographic analysis of the feeding movements in Varanus bengalensis produced the following results. The mouth is opened by raising the head (upper jaw) rather than by lowering the lower jaw. Starting from the resting position, the muzzle unit is elevated around 9 degrees relative to the rest of the skull during jaw opening; the quadrate swings anteriorly around 21 degrees. During jaw closure, the snout is depressed around 15 degrees relative to the rest of the skull, hence 6 degrees beyond the resting position. The quadrate swings backwards around 27 degrees. Amphikinesis is interpreted as allowing a stronger posterior recurvature of the maxillary teeth in Varanus. This increases the holding effect of the teeth without increasing their length, an adaptation of Varanus to capture relatively large prey. The formation of plicidentine (dentine infolding) in the teeth of Varanus increases the surface of attachment of the teeth on the supporting bone. Moreover, the dentine lamellae take up tensile and compressive stresses along their long axes upon axial or vertical loading of the teeth. The slope of pleurodonty is modelled so as to minimalize shear stress on the surface of ankylosis upon axial or vertical loading of the teeth.

Animals↗
PubMed1976

Functional anatomy of the hands of fur seals and sea lions.

Dissections and manipulations of the hands of 14 specimens of four genera of fur seals and sea lions and of generalized fissiped carnivores were used to identify the structural modifications involved in formation of the expanded forelimb paddles characteristic of these pinnipeds. The morphological peculiarities were then correlated with differences in locomotor function, both on land and in the water, on the basis of previously published data, for the purpose of identifying modifications of structure and function which have adaptive vale. Structural differences found in the manus of fur seals and sea lions include: (1) reduction in size of the ulnar side of the carpus and a radial shift in the length-order of the digits, (2) development of musculature in the antebrachial fascia which attaches to the caudal margin of the flipper, (3) orientation of the radial side of the manus dorsal and radial to the rest of the hand, (4) increased range of possible midcarpal movement and in deviational mobility at the first and fifth digits, (5) attachment of forearm musculature onto radial digits and (6) well-developed hypothenar muscles and absence of thenar muscles. Modifications in hand structure are viewed as providing a morphological basis for employment of the hand to advantage during aquatic locomotion while maintaining thrust-producing and potentially energy-conserving capacities during movement on land. As such these differences in structure and function are viewed as adaptations to locomotion in the water and on land which are extensions of locomotor adaptations attributed to modifications of forelimb structure and function associated with the generation of massive aquatic locomotor thrust. The adaptive value of such modifications is interpreted as allowing fur seals and sea lions to swim with speed and thereby capture elusive fast-swimming prey while maintaining a level of terrestrial locomotor ability compatible with their amphibious mode of life.

Animals↗
PubMed1978

Some questions related to mechanisms of slave-raids in Amazon-ant Polyergus rufescens Latr.

A new hypothesis concerning the mechanism of the P. rufescens' slave-raids, is proposed. (i) The so-called pseudo-scouting does not contribute to the slave-raids. (ii) The direction of the raid is determined by the random movement of the most easily aroused individuals - the so-called activists. (iii) Once the direction has been set the army marches straight ahead and returns by the same road orienting itself by visual stimuli; single individuals who lag behind can however follow the scent-trial which had been left by the army. (iv) The slave-capturing instinct of the amazons is not directed at the abduction of pupae alone but also and even perhaps primarily at the abduction of mature individuals belonging to the slave-species; that the amazons bring almost only pupae is caused by the fact that the mature individuals offer resistance and are consequently a more troublesome prey.

Animal Communication↗
PubMed1979

Optimal body size and an animal's diet.

Within many animal taxa there is a trend for the species of larger body size to eat food of lower caloric value. For example, most large extant lizards are herbivorous. Reasonable arguments based on energetic considerations are often invoked to explain this trend, yet, while these factors set limits to feasible body size, they do not in themselves mathematically produce optimum body sizes. A simple optimization model is developed here which considers food search, capture, and eating rates and the metabolic cost of these activities for animals of different sizes. The optimization criterion is defined as the net calorie gain a consumer accrues per day. This model does produce an optimum intermediate body size which increases with food quality--not the reverse. This discrepancy is accounted for, however, because the model also predicts that body size should be even more sensitive to increases in food abundance. In nature, many poor quality foods are also relatively abundant foods, hence the consumers eating them may maximize their daily energetic profit by evolving a relatively large body size. Optimum consumer body size also decreases with increases in consumer metabolic rate and "prey" speed.

Animals↗