The Science of Nature最新文献

Many teleost fishes are capable of sex change, and some species possess intersex gonads known as ovotestes, which contain both ovarian and testicular tissues. Uncovering the developmental processes in ovotestis formation is critical for elucidating the mechanisms of intersexuality in vertebrates. However, such developmental processes have been described in only a limited number of species. In this study, we examined the histological structure of juvenile gonads in the harlequin sandsmelt (Parapercis pulchella), a female-to-male sex-change fish in which mature females possess ovotestes. Juveniles measuring up to 32.2 mm in total length exhibited gonads containing cyst-formed developing oogonia and a small number of oocytes. In contrast, larger juveniles possessed more developed ovaries but showed no detectable spermatogenic germ cells. These results suggest that gonads initially differentiate as ovaries and subsequently develop into ovotestes through the emergence of male germ cells. Together with previous studies, our results also indicate that a similar developmental sequence may be shared among sex-change fishes.

The elytra of ladybird beetles serve not only as protective structures but also as key surfaces for chemical communication during reproduction. In this study, we investigated the role of elytral surface chemicals in mating behaviour of Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) by experimentally manipulating chemical cues. Treatments included removal of surface chemicals, exchange of cuticular extracts, and coating of elytra with ink-based solvents that varied in persistence. Mating behaviour was assessed using two parameters: time to commence mating (TCM) and copulation duration (CD). Our results showed that persistent coatings caused the longest delays in mating initiation and the shortest copulation durations, suggesting strong interference with natural chemical signals. Temporary coatings also disrupted mating, though less severely, while solvent-washed and exchanged treatments produced moderate effects. Control groups, including handling and solvent-only treatments, did not differ significantly, confirming that the observed effects were due to chemical manipulations. Importantly, no treatment completely inhibited reproduction, highlighting the robustness of C. sexmaculata and the likely use of multiple sensory pathways in mate recognition. This work demonstrates that sexual recognition compounds on elytra plays a crucial role in mating communication but also reveals the adaptive resilience of C. sexmaculata when cues are disrupted. By showing that reproduction persists despite experimental interference, our study provides insight into the flexibility of insect communication systems and strengthens the case for C. sexmaculata as a reliable biological control agent under variable ecological and chemical conditions.

Social insect colonies rely on accurate brood recognition to maintain colony integrity and reproductive success. In termites, however, this recognition system is exploited by egg-mimicking fungal sclerotia known as “termite balls,” which are transported and tended by workers. Yet the mechanisms underlying these recognition errors are not well understood. Here we show that egg recognition in Reticulitermes speratus involves a speed–accuracy trade-off, where faster egg-pile formation leads to more frequent acceptance of mimics, and that this trade-off is seasonally modulated, potentially generating a predictable window for social parasitism during peak reproductive periods. In the season when eggs were present, workers formed egg piles more quickly and transported dummy eggs (glass beads coated with egg-recognition pheromone) more readily than when eggs were absent. Importantly, even in off-season colonies lacking eggs, repeated transport trials, using eggs supplied from laboratory-maintained colonies, sensitized workers to transport both eggs and mimics. Across trials, we observed a speed–accuracy trade-off: faster pile formation was associated with a higher proportion of mimics mistakenly included in the egg pile. This behavioral plasticity, while adaptive for efficient brood care during peak reproductive seasons, inadvertently increases susceptibility to parasitic infiltration. The egg-mimicking fungus Athelia termitophila is consistent with this mechanism, as its termite-ball sclerotia are treated as eggs by workers. Our results show that seasonal changes in colony workload modulate the balance between speed and accuracy in brood recognition, revealing a behavioral mechanism through which predictable vulnerabilities can arise in social insect colonies.

Female mimicry is a reproductive tactic typically employed by small males (minors) in species with female- or resource-defense polygyny. By mimicking females, minors may secure copulations without being detected by territorial males (majors). We used three complementary approaches to investigate the possibility of female mimicry in the male-dimorphic harvestman Serracutisoma proximum, a chemically-oriented arachnid with a resource-defense mating system. Minors rely primarily on sneak copulations, and if they exhibit female mimicry, we expect them to elicit behavioral responses from majors similar to those directed toward females. Indeed, a field experiment showed that majors displayed reduced aggression toward minors and even attempted copulation with some of them. To examine the mechanisms underlying of mistaken sex identification, we compared the cuticular chemical profiles of majors, minors, and females, and quantified the density of chemoreceptors on the sensory legs of majors and minors. Contrary to female mimicry predictions, the overall chemical profile of minors did not resemble that of females. However, some compounds that signal female reproductive status in spiders showed similar abundances in minors and females. Additionally, chemoreceptor density did not differ between majors and minors, suggesting that mistaken sex identification is also not due to sensory limitations in majors. In conclusion, while behavioral evidence is consistent with female mimicry, the underlying mechanisms remain unresolved. Regardless of the underlying mechanism, the ability of some minors to access and mate with females even in the presence of majors likely confers reproductive advantages, which could maintain alternative reproductive tactics within the population.

Geophagy, the ingestion of earthy materials such as soil or sand, is present in different animal groups, including adult frogs and their larvae. In some species, the ingestion of sediments is an intrinsic aspect of the biology of these animals. During an investigation on aspects of the natural history and morphology of tadpoles of Thoropa miliaris (Cycloramphidae) we noticed that their intestines were filled with sediments. The first question that occurred to us involved whether ingestion was accidental or part of their behavioral repertoire. These tadpoles are found in rockfaces wetted by a slow running film of water, where besides a slime film of algae and moss, we do not observe significant accumulation of sediments. Another question involved knowing if the sediments ingested were already available in their habitat, or if they were biting off small pieces of the rocks where they live. To investigate that, we used a combination of light microscopy and synchrotron high-resolution x-ray microtomography techniques to study the morphology of the sediments in the habitat and intestines of 57 tadpoles in different stages of development (all with sediments in their digestive tracts) and based on that, determine its source. Comparisons of geometric features of the sediments on the habitat and in the tadpoles’ intestines, favor the hypothesis that its source is already present in the habitat and that it is swallowed as water and food is sucked as part of the tadpole foraging and respiratory behavioral repertoire.

Antennae are vital insect sensory organs, primarily used for interactions with other organisms and the detection of the environment. Bipectinate antennae have evolved independently in the insect orders Lepidoptera, Coleoptera, Hymenoptera, Diptera and Cretaceous Mecoptera, Neuroptera, Trichoptera, and Blattaria. However, among Blattaria they are extremely rare and bipectinate antennae have been known only from one mid-Cretaceous species, while pectinate antennae were documented in two mid-Cretaceous species and one extant species from China. Here we describe Pinniblatta sylvana gen. et sp. nov., P. horvathovae sp. nov. and Cupidoblatta elegans gen. et sp. nov. with bipectinate antennae, all belonging to the family Corydiidae, and discovered from northern Myanmar amber. We also reassigned the genera Ol Vršanský et Wang, 2017 and Olenoblatta Šmídová 2022 to the family Corydiidae. The presence of pectinate and bipectinate antennae in males only (in 9 specimens) is likely due to sexual selection. In addition, the antennal ultrastructure, featuring an increased number of chemoreceptors, likely trichoid sensilla on the pectinae, could have served to detect female pheromones. This discovery significantly expands the known diversity of the extremely rare bipectinate antennae among Blattaria.

Climate change poses a severe long-term threat to endemic species. Ecologists must have a comprehensive understanding of habitat suitability and environmental variables that control their distribution to minimize biodiversity loss and improve conservation strategies effectively. The MaxEnt model is commonly applied to predict species distribution based on occurrence data and environmental variables. This study investigated the suitable habitats of the endemic Quercus afares in Algeria, evaluated shifts in its range under climate change scenarios and identified the key ecological factors determining its distribution. The results showed that the Area Under the Curve (AUC = 0.992) indicated excellent performance of our MaxEnt model. The major environmental predictor for Quercus afares was the Martonne aridity index (Idm), which had the most useful information. Future scenarios indicate that the highly suitable habitat for Quercus afares is expected to range between 0.2% and 0.14%. The average elevation of suitable habitat changes according to each climate scenario, ranging from 1,086.5 to 1,276.5 m. The highly suitable habitat shifts towards the northeast in most future climate scenarios. Our findings represent a decision support tool and contribute to developing effective conservation and management measures of Quercus afares in Algeria.

This study aims to design and synthesize novel benzothiazole based thiazolidinone derivatives as potential inhibitors of carbohydrate-hydrolyzing enzymes, addressing the urgent need for effective therapeutic agents to manage type 2 diabetes mellitus through enzymatic regulation. All the novel benzothiazole based thiazolidinone derivatives were investigated against α-amylase and α-glucosidase with significant potential for treating a common metabolic problem, diabetes mellitus. The synthesis of these derivatives was confirmed using ¹HNMR, ¹³CNMR, and HREI-MS. Biological assessment was carried out by comparing the new analogs with acarbose (IC₅₀ = 5.40 ± 0.30 µM for α-amylase and 5.70 ± 0.50 µM for α-glucosidase). The synthesized analogs exhibited a range of inhibitory activities with IC₅₀ values for α-amylase ranging from 19.30 ± 0.20 µM to 3.60 ± 0.10 µM and for α-glucosidase ranged from 20.60 ± 0.40 to 4.40 ± 0.20 µM. Notably, compound 9 with a trifluoromethyl group showed significant binding interaction, contributing to its high potency. Molecular docking studies provided insights into the binding interactions of all the potent analogs, while density functional theory (DFT) calculations explored the stability and reactivity of the active compounds. Additionally, ADMET analysis was conducted for examining drug-likeness of the potent compounds.

The littoral bryozoan communities in the Barents and Greenland Seas have not received as much attention as their deep-water communities. To address this gap, we compared the diversity and biomass patterns of bryozoans across two localities: Eastern Murman (EM), (southern Barents Sea, 69°N) and Grønfjorden (GF), Svalbard (Greenland Sea, 78°N). The study revealed moderate dissimilarity in habitat conditions. Boreo-Arctic species were the most common at both sites, but the proportion of boreal species was higher in EM (28 vs. 7.5%). Biomass tended to be higher at higher latitudes. Multivariate analyses revealed a significant dissimilarity of 94.1% between bryozoan communities at the two study sites. Redundancy analysis demonstrated that substrate type was the primary driving force for bryozoans in GF, whereas diversity indices were positively associated with salinity in EM, and bryozoan biomasses were negatively scaled to temperature. These differences may be attributed to the more stressful conditions in EM, where thermal stress may act as an initial stressor, leading to a reduction in salinity levels that negatively impact bryozoans, rendering them unable to survive in less saline water as they do in GF under more optimal temperature conditions.

The dual global health crises of antimicrobial resistance and cancer demand the urgent discovery of novel therapeutic leads. The medicinal plants Cynanchum viminale and Pergularia daemia (Apocynaceae) represent a rich reservoir of bioactive compounds used in traditional medicine, yet a comprehensive comparative analysis of their bioactivities and molecular mechanisms has remained elusive. This study provides an integrated in vitro and in silico analysis of the methanolic extracts of C. viminale and P. daemia. Phytochemical profiles were delineated by HPLC. Bioactivities were systematically evaluated via a battery of five antioxidant assays (DPPH, ABTS, FRAP, H₂O₂, NO), broad-spectrum antimicrobial screening against six pathogens, and cytotoxicity assays against a panel of six human cancer cell lines (HepG-2, MCF-7, HCT-116, A-549, PC-3, A-431). To deconstruct the molecular basis of these activities, in silico molecular docking was performed against two pivotal therapeutic targets: Epidermal Growth Factor Receptor (EGFR) and Dihydrofolate Reductase (DHFR). A striking functional divergence between the two plants was discovered. P. daemia exhibited superior antioxidant and broader-spectrum antibacterial activity, a finding strongly correlated with its unique phenolic profile, particularly the potent DHFR-binding Chlorogenic acid and the bioenhancing alkaloid Piperine. In stark contrast, C. viminale demonstrated dramatically superior cytotoxic potency across all tested cancer cell lines, with IC₅₀ values as low as 24.37 µg/mL against HepG-2 liver cancer. Molecular docking brilliantly illuminated the mechanism behind this divergence: the potent cytotoxicity of C. viminale is driven by its principal alkaloids, Protopine and Berberine, which showed high-affinity binding to the ATP-binding site of EGFR, a key driver of cancer proliferation. DHFR, conversely, was identified as a common molecular target for potent binders from both plants (Evodiamine, Piperine, Chlorogenic acid), providing a unifying mechanism for their shared antimicrobial properties.