The Biomechanics of the Locust Ovipositor Valves: a Unique Digging Apparatus

The female locust has a unique mechanism for digging in order to deposit its eggs deep in the ground. It utilizes two pairs of sclerotized valves to displace the granular matter, while extending its abdomen as it propagates underground. This ensures optimal conditions for the eggs to incubate, and provides them with protection from predators. Here, two major axes of operation of the digging valves are identified, one in parallel to the propagation direction of the ovipositor, and one perpendicular to it. The direction-dependent biomechanics of the locust major, dorsal digging valves are quantified and analyzed, under forces in the physiological range and beyond, considering hydration level, as well as the females age, or sexual maturation state. Our findings reveal that the responses of the valves to compression forces in the specific directions change upon sexual maturation to follow their function, and depend on environmental conditions. Namely, in the physiological force range, the valves are resistant to mechanical failure. In addition, mature females, which lay eggs, have stiffer valves, up to roughly nineteen times the stiffness of the pre-mature locusts. The valves are stiffer in the major working direction, corresponding to soil shuffling and compression, compared to the direction of propagation. Hydration of the valves reduces their stiffness but increases their resilience against failure. These findings provide mechanical and materials guidelines for the design of novel non-drilling excavating tools, including 3D-printed anisotropic materials based on composites.

Allometry of the box crab Calappa convexa De Saussure, 1853 (Brachyura, Calappidae) in the southeastern Gulf of California

The relative growth of Calappa convexa can be used to identify dimorphism or morphological change related to sexual maturation. The carapace width (CW) against width and length of the propodus of the right and left cheliped were tested to obtain a coefficient of allometry. CW against total wet weight WT values were analysed for length-weight relationships (LWR). Relative growth was analysed by a multi-model approach. Five models were tested and the best was selected due to the greater weight of the Akaike criterion (). Significant differences between sexes were found in CW (, ) and WT (, ). The negative or positive allometry varied according to the morphometric relationship and sex. No real winner model () was observed in the LWR analysis under a multi-model approach. The average model estimated a breakpoint at 118 mm CW in males and 132 mm CW in females.

MORPHOFUNCTIONAL CHARACTERISTICS THYROID GLAND OF WHITE-BREASTED MALE HEDGEHOG IN THE PERIOD OF PUBERTY

The issue of the morphofunctional characteristics of the thyroid gland of male white-breasted hedgehogs during puberty on the territory of Belarus was studied. Material for the study was taken from 15 males, who were divided into three stages of studying the sexual maturation of hedgehogs: stage I - prepubertal period, stage II - the beginning of puberty, and stage III - activation of the gonads and the end of puberty. The results obtained characterize the morphological state of the thyroid gland of male white-breasted hedgehogs during puberty, and thus makes it possible to use morphometric indicators of structures as indicators of the environment and physiological states (for assessing puberty).

The X-ray structure of juvenile hormone diol kinase from the silkworm Bombyx mori

Insect juvenile hormones (JHs) are a family of sesquiterpenoid molecules that are secreted into the haemolymph. JHs have multiple roles in insect development, metamorphosis and sexual maturation. A number of pesticides work by chemically mimicking JHs, thus preventing insects from developing and reproducing normally. The haemolymph levels of JH are governed by the rates of its biosynthesis and degradation. One enzyme involved in JH catabolism is JH diol kinase (JHDK), which uses ATP (or GTP) to phosphorylate JH diol to JH diol phosphate, which can be excreted. The X-ray structure of JHDK from the silkworm Bombyx mori has been determined at a resolution of 2.0 Å with an R factor of 19.0% and an R free of 24.8%. The structure possesses three EF-hand motifs which are occupied by calcium ions. This is in contrast to the recently reported structure of the JHDK-like-2 protein from B. mori (PDB entry 6kth), which possessed only one calcium ion. Since JHDK is known to be inhibited by calcium ions, it is likely that our structure represents the calcium-inhibited form of the enzyme. The electrostatic surface of the protein suggests a binding site for the triphosphate of ATP close to the N-terminal end of the molecule in a cavity between the N- and C-terminal domains. Superposition with a number of calcium-activated photoproteins suggests that there may be parallels between the binding of JH diol to JHDK and the binding of luciferin to aequorin.

Characterization of N6-Methyladenosine in Domesticated Yak Testes Before and After Sexual Maturity

The potential regulatory role of N6-methyladenosine (m6A), the most prominent mRNA modification in eukaryotes, has recently been identified in mammals, plants, and yeast. However, whether and how m6A methylation is involved in sexual maturation in mammals remains largely unexplored. In this study, testicular tissue was obtained from yaks before and after sexual maturation, and m6A maps were generated via preliminary experiments and methylated RNA immunoprecipitation sequencing. Only spermatogonial cells and a few primary spermatocytes were observed in the testicular tissue of yaks before sexual maturation, while spermatogenic cells at different stages of maturity could observed after sexual maturation. Experiments examining the expression of methylation-related enzymes and overall methylation levels showed that the methylation levels in yak testes increased after sexual maturation. Overall, 1,438 methylation peaks were differentially expressed before and after sexual maturation; 1,226 showed significant up-regulation and 212 showed significant down-regulation after sexual maturation. Annotation analysis showed that the differential methylation peaks were most commonly concentrated in the exon region, followed by the 3′UTR and finally the 5′UTR region. KEGG pathway analysis demonstrated that homologous recombination, the Notch signaling pathway, growth hormone synthesis, and other signaling pathways may be involved in testicular development and maturation in yaks. Levels of most m6A modifications were positively correlated with mRNA abundance, suggesting that m6A plays a regulatory role in mammalian sexual maturation. To our knowledge, this is the first report of an m6A transcriptional map of the yak testes, and our study lays the foundation for elucidating the function of m6A in the development of yak testes.

ИССЛЕДОВАНИЕ РОСТА, РАЗВИТИЯ И РАЗМНОЖЕНИЕ ОБЫКНОВЕННОГО СОМА (SILURUS GLANIS L.) НА РЕКЕ УРАЛ

The features of growth, development and maturation of common catfish in the reservoirs of the Urals are studied. It is established that in the periods 1+ to 3+ the body length of the common catfish increases 2.29 times, the live weight up to 8.42 times. The ratio of live weight and length to the intestine in catfish 2+ is 1:0.43, in six-year-olds 1: 31.14 times. Sexual maturation of catfish occurs at the age of 4+ years, they have counted 86761 pieces of eggs, in six-year-olds 423810 pieces. or 4.88 times more.