Body Size Of Larvae Research Articles

Drosophila NSD deletion induces developmental anomalies similar to those seen in Sotos syndrome 1 patients.

Haploinsufficiency of the human nuclear receptor binding suppressor of variegation 3-9, enhancer of zeste, and trithorax (SET) domain 1 (NSD1) gene causes a developmental disorder called Sotos syndrome 1 (SOTOS1), which is associated with overgrowth and macrocephaly. NSD family proteins encoding histone H3 lysine 36 (H3K36) methyltransferases are conserved in many species, and Drosophila has a single NSD homolog gene, NSD. To gain insight into the biological functions of NSD1 deficiency in the developmental anomalies seen in SOTOS1 patients using an NSD-deleted Drosophila mutant. We deleted Drosophila NSD using CRISPR/Cas9-mediated targeted gene knock-out, and analyzed pleiotropic phenotypes of the homozygous mutant of NSD (NSD-/-) at various developmental stages to understand the roles of NSD in Drosophila. The site-specific NSD deletion was confirmed in the mutant. The H3K36 di-methylation levels were dramatically decreased in the NSD-/- fly. Compared with the control, the NSD-/- fly displayed an increase in the body size of larvae, similar to the childhood overgrowth phenotype of SOTOS1 patients. Although the NSD mutant flies survived to adulthood, their fecundity was dramatically decreased. Furthermore, the NSD-/- fly showed neurological dysfunctions, such as lower memory performance and motor defects, and a diminished extracellular signal-regulated kinase (ERK) activity. The NSD-deleted Drosophila phenotype resembles many of the phenotypes of SOTOS1 patients, such as learning disability, deregulated ERK signaling, and overgrowth; thus, this mutant fly is a relevant model organism to study various SOTOS1 phenotypes.

Low larval densities in northern populations reinforce range expansion by a Mediterranean damselfly

Summary Contemporary climate change triggers a poleward range shift in many species. A growing number of studies document evolutionary changes in traits accelerating range expansion (such as growth rate and dispersal‐related traits). In contrast, the direct impact of decreasing conspecific densities towards the very edge of the expansion front has been neglected. Density effects may, however, have a profound direct impact on traits involved in range expansion and influence range dynamics. In this study, we contrast the effects of high conspecific larval density typical for established populations and low larval density typical for newly founded populations at the edge of the expansion front on a set of larval traits that may affect the range dynamics in the poleward moving damselfly Coenagrion scitulum. We therefore ran an outdoor mesocosm experiment with a low‐ and high‐density treatment close to the species’ northern expansion front. Density effects on survival, growth rate and body size are scored both during the pre‐winter growth period and during the subsequent winter period. Additionally, foraging activity was scored at the end of the pre‐winter period and body condition [size‐corrected body mass, fat content and activity of phenoloxidase (PO)] was scored at the end of the winter period. The low‐density treatment had strong direct positive effects on survival, growth rate and body size of larvae before winter indicating relaxed competition. Lower foraging activity at the low‐density treatment indicated higher food availability at low conspecific densities. Interestingly, the initial density treatment had stronger effect than densities experienced at the time of quantification on survival during the pre‐freezing winter period and body condition estimates at the end of the experiment, indicating also delayed effects of the initial density treatment. Survival throughout a freezing period indicated extreme winter conditions are not likely a limiting factor in the range expansion of this Mediterranean species. The increased survival and individual growth rates (through causing shifts in voltinism) at low conspecific density will translate in increased population growth rates. Furthermore, nutritional advantages at low conspecific density may increase investment in dispersal ability. Together, these direct and delayed density‐dependent effects that gradually increase towards the expansion front are expected to accelerate range expansion.

Larval growth rate and sex determine resource allocation and stress responsiveness across life stages in juvenile frogs.

The extent to which interactions between environmental stressors and phenotypic variation during larval life stages impose carry-over effects on adult phenotypes in wildlife are not clear. Using semi-natural mesocosms, we examined how chronically low food availability and size-specific phenotypes in larval amphibians interact and carry over to influence frog growth, resource allocation, endocrine activity and survival. We tagged three cohorts of larvae that differed in body size and developmental stage at 3 weeks after hatching, and tracked them through 10 weeks after metamorphosis in high and low food conditions. We found that growth and development rates during the early tadpole stage not only affected metamorphic rates, but also shaped resource allocation and stress responsiveness in frogs: the slowest growing larvae from low-food mesocosms exhibited a suppressed glucocorticoid response to a handling stressor; reduced growth rate and fat storage as frogs. We also show for the first time that larval developmental trajectories varied with sex, where females developed faster than males especially in food-restricted conditions. Last, while larval food restriction profoundly affected body size in larvae and frogs, time to metamorphosis was highly constrained, which suggests that the physiology and development of this ephemeral pond-breeding amphibian is adapted for rapid metamorphosis despite large potential variation in nutrient availability. Taken together, these results suggest that larval phenotypic variation significantly influences multiple dimensions of post-metamorphic physiology and resource allocation, which likely affect overall performance.

Redescription and genetic characterization of Philometra lagocephali Moravec et Justine 2008 (Nematoda: Philometridae) from Lagocephalus lunaris (Bloch and Schneider) (Tetraodontiformes: Tetradontidae) in the South China Sea.

Philometra lagocephali Moravec et Justine, 2008 was redescribed using light and scanning electron microscopy based on the new material collected from the lunartail puffer Lagocephalus lunaris (Bloch et Schneider) (Tetraodontiformes: Tetradontidae) in the South China Sea. Our specimens are identical with the original description in the body size of gravid female, the width of cephalic and caudal end, the number and arrangement of cephalic papillae, the relative length of the oesophagus to body length, the size of ventriculus, the morphology of oesophageal bulb and posterior end, and the body size of larvae. In addition, specimens of P. lagocephali were also characterized using molecular methods by sequencing and analysing the small ribosomal DNA (18S rDNA) and mitochondrial cytochrome c coxidase subunit 1 (cox1) target regions. Phylogenetic analyses of genus Philometra base on 18S rDNA sequences was made using Mega 5.2. The results confirmed P. lagocephali is a valid species. It's the first molecular study of this species. These new morphological and molecular data contributed to a more precise and rapid diagnosis of this hitherto poorly known philometrid nematode.

Exposure-dependent variation in cryolite induced lethality in the nontarget insect, Drosophila melanogaster

The starting point of toxicity testing of any chemical in an organism is the determination of its Lethal Concentration 50 (LC50). In the present study, LC50 of a fluorinated insecticide cryolite is determined in a non-target insect model, Drosophila melanogaster. Interestingly, the result shows that acute LC50 of cryolite was much greater in comparison to the chronic one in case of Drosophila larvae. Larvae which were exposed to 65,000 to 70,000 µg/ml cryolite through food showed 50% mortality after 18 hours of acute exposure, whereas only 150 to 160 µg/ml cryolite was sufficient to cause 50% mortality in case of chronic exposure. Thus cryolite in a small amount when applied once cannot produce noticeable changes in Drosophila, whereas the same amount when used continuously can be fatal. The non-feeding pupal stage was also seen to be affected by chemical treatment. This suggests that the test chemical affects the developmental fate and results in failure of adult emergence. Absence of chemical-induced mortality in adults assumes that the toxicity of cryolite might be restricted to the preimaginal stages of the organism. Reduction in body size of larvae after ingestion of cryolite (with food) in acute treatment schedule is another interesting finding of this study. Some individuals consuming cryolite containing food cannot survive whereas the few survivors manifest a significant growth retardation which might be due to a tendency of refusal in feeding. Hence the present findings provide a scope of assessment of risk of other similar non-target groups.

Jack of all trades masters novel host plants: positive genetic correlations in specialist and generalist insect herbivores expanding their diets to novel hosts

One explanation for the widespread host specialization of insect herbivores is the 'Jack of all trades-master of none' principle, which states that genotypes with high performance on one host will perform poorly on other hosts. This principle predicts that cross-host correlation in performance of genotypes will be negative. In this study, we experimentally explored cross-host correlations and performance among families in four species (two generalist and two specialist) of leaf beetles (Cephaloleia spp.) that are currently expanding their diets from native to exotic plants. All four species displayed similar responses in body size, developmental rates and mortality rates to experimentally controlled diets. When raised on novel hosts, body size of larvae, pupae and adults were reduced. Development times were longer, and larval mortality was higher on novel hosts. Genotype × host-plant interactions were not detected for most traits. All significant cross-host correlations were positive. These results indicate very different ecological and evolutionary dynamics than those predicted by the 'Jack of all trades-master of none' principle.

Color variability and body size of larvae of two Epomis species (Coleoptera: Carabidae) in Israel

Species identification using the characteristics of developmental stages is challenging. However, for insect taxonomy the coloration of larval stages can be an informative feature. The use of live specimens is recommended for this because the color fades in preserved specimens. In this study we examine the possibility of using variation in coloration and color pattern of larvae in order to distinguish between twoground beetlesspecies Epomis dejeani (Dejean, 1831) and Epomis circumscriptus (Duftschmid, 1812). We present an atlas and describe the coloration and body size of the three larval stages of the above species based on live specimens. An identification key is given for the three larval instars of the two Epomis species.The first instar larvae of the two Epomis species can be easily distinguished based on their color. From the second instar on, the variability in coloration and color patterns increases, creating an overlap in these attributes between larvae of the two species. Except for minor differences in color of the antennae and the base of the mandibles, larvae of the two species are indistinguishable at the second and third larval stages. To the best of our knowledge this is the first attempt to use variation in coloration and color pattern in live larvae in order to identify coleopterans. The color atlas of the larvae enables simple separation of the two Epomis species without requiring sophisticated magnifying devices, although it is less straightforward at the second and third larval stages.We found similar body lengths between the two species for all developmental stages, except for third instar larvae prior to pupation. In the two species the difference in larval body length before pupation positively correlated with that of the adult beetles. More than 70% of the adults’ length can be explained by the length of the late third-instar larva; i.e. the large larvae develop into large adults. The larger specimens are the females.

Dependence of the weight on linear dimensions of the body in three chironomid species larvae (Diptera, Chironomidae) from the Lake Baikal littoral

The body size of larvae and the age structure of populations of three chironomid species (Chironomidae) from the Lake Baikal littoral was studied. Young larvae 1.0–2.6 mm long were abundant during the whole period investigated (August 2000–August 2001). Parameters of the equation that allows determining the weight of midge larvae by the width of their head capsule or by their body length were calculated for Paratanytarsus baicalensis, Orthocladius nitidoscutellatus, and Orthocladius sp.

Effect of river run-off on the distribution of marine invertebrate larvae in the southern Kara Sea (Russian Arctic)

Within the generally oligotroph Arctic marine environment river outlets are favoured by many planktonic and benthic organisms due to their high input of organic carbon. The retention of pelagic larvae within nursery grounds and/or the ability to return to their parental grounds prior to settlement is one important factor for the persistence of benthic communities in such river influenced areas. The southern Kara Sea is strongly controlled by high freshwater inputs from the Ob and Yenisei Rivers, which create a pronounced bi-layered pycnocline with a warm fresh/brackish water layer on top and a cold high saline marine layer below. The dispersal of five meroplanktonic species and settled juveniles (the brittle star Ophiocten sericeum, and the polychaetes Micronephtys minuta, Nereimyra aphroditoides, Phyllodoce groenlandica and Prionospio cirrifera) in relation to the adult distribution patterns was investigated. For all apart from P. cirrifera the highest densities of larvae were found in the upper brackish water layer. To assess size-at-settlement, the body sizes of larvae and newly settled juveniles were estimated and compared. Dispersal patterns ranged from virtually no adaption to river run-off as in the common, stenohaline O. sericeum and M. minuta (7 ind. m − 3 , 459 μm) to local retention as in N. aphroditoides (7 ind. m − 3 , 541 μm) and P. groenlandica (0.5 ind. m − 3 , 1121 μm) retained by horizontal eddies created by the outflow. Adults of P. cirrifera, which were exclusively restricted to the estuary of the Yenisei River, showed a well adapted reproductive behaviour to ensure a high retention potential of their progenies. The larvae (1.5 ind. m − 3 , 1513 μm) were only present in the lower water layers, most probably taking advantage of the prevailing near bottom counter current retaining them within their hatching areas.

Evolution of conspicuous colouration, body size and gregariousness: a comparative analysis of lepidopteran larvae

Protective colouration in animals includes camouflage (i.e., crypsis), that decreases the risk of detection, and conspicuous colouration, which is often used in combination with chemical defences to deter predators from attacking. Experiments have shown that the efficacy of conspicuous colouration increases with increasing size of pattern elements and larger body size. Prey species that have acquired avoidance inducing colouration therefore may be exposed to selection for larger body size, and such colouration may more easily evolve in large than in small prey species. Here we test for a difference in body size between species with different colouration modes and perform a comparative analysis based on phylogenetically independent contrasts to examine if evolutionary shifts in colour pattern have been associated with evolutionary changes in body size, using data for 578 species of moths. Larval body size did not differ between species with signalling and non-signalling larvae, and results from the comparative analysis suggest that these two traits have not evolved in parallel. The lack of association between evolutionary changes in colouration and body size may reflect a confounding influence of lifestyle, because evolutionary shifts from solitary to group-living larvae were associated with decreased larval body length and adult wing span. Because evolutionary changes in larval body size were associated with evolutionary changes in adult wing span the predicted association between colouration and size may have been confounded also by conflicting selection on body size in larvae and adults.

Effect of single cell protein as a protein source in Drosophila culture

The effects of biomass of Phanerochaete chrysosporium at various concentrations (1; 2.5; 5; 10; 25; 50; 75 and 100%) on the growth of Drosophila melanogaster have been investigated. Biomass was used as a protein source instead of corn flour in Standard Drosophila Medium(SDM). It was seen that it causes increments in both body size of larvae and the numbers of offsprings, especially at higher concentrations (50, 75 and 100%). At the application of 100% concentration, metamorphosis accelerated and was completed one day before the control. There were phenotipic abnormalities in both control (0.64%) and applications with low concentrations (0.02-0.19%), while they were not observed at the application of 100% concentration

Paedomorphosis in Ambystoma Talpoideum: Effects of Density, Food, and Pond Drying

The expression of metamorphosis and paedomorphosis in the salamander Ambystoma talpoideum was examined in a three—factor experiment using artificial ponds. This experiment was designed to measure simultaneously the effects of initial larval density, food level, pond drying regime, and their interactions on the percentage of individuals metamorphosing or becoming paedomorphic. A higher percentage of individuals metamorphosed from drying low—density, and high—food ponds than from constant water level, high—density, and low—food ponds. A higher percentage of individuals became paedomorphic in constant water—level and low—density ponds than in drying and high—density ponds. Food level had no effect on the expression of paedomorphosis. Initial density, food level, and drying regime all had significant effects on the mean snout—vent length of larvae in ponds. The percentage of paedomorphic individuals in a pond was positively correlated with mean snout—vent length in the population. Analysis of covariance using snout—vent length as the covariate removed density and food level effects on the percentage of metamorphic individuals but did not remove the effects of drying regime. Use of snout—vent length as covariate in an analysis of covariance for the percentage of paedomorphic individuals failed to remove significant effects of density or drying regime. Only initial density affected the survival of larvae. The factors manipulated in this experiment affected the expression of paedomorphosis both directly through the physical environmental conditions that they created and indirectly through the growth and body size of larvae. These results suggest that differences in environmental factors among populations can affect the life—history pathways of individuals and lead to a predominance of paedomorphosis in permanent aquatic habitats with favorable growth environments.

Effect of hypoxia and body size on the energy metabolism of lungless tadpoles, Bufo woodhousei, and air‐breathing anuran larvae

AbstractUnlike most anuran larvae, tadpoles of Bufo woodhousei (toads) lack lungs. To investigate the consequences of lunglessness and its interaction with the body size of larvae, resting and active tadpoles were exposed to hypoxia. In resting larvae, rates of O2 consumption (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document}) were proportional to aquatic PO2, even though larvae increased buccopharyngeal ventilation considerably in hypoxia. Whole body lactate concentrations increased only in severe hypoxia. Hypoxia also depressed the \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} of active larvae, which accumulated lactate even in normoxic water. Air‐ and water‐breathing tadpoles (Rana berlandieri and Xenopus laevis) can maintain greater routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia than can Bufo tadpoles. However, Bufo tadpoles can extract more O2 from hypoxic water than can Rana and Xenopus tadpoles, when all are breathing only water.The critical Po2 of active larvae and the gill ventilatory frequency of resting larvae were proportional to body size. By contrast, large and small Bufo tadpoles were similar in routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia, the ration \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} max:\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} routine, and tolerance of hypoxia. Also, small tadpoles accumulated more lactate than large tadpoles when swimming at similar absolute velocities for the same times. Thus, lunglessness apparently does not limit the size of Bufo tadpoles by forcing reliance upon cutaneous gas exchange.