Pseudo-nitzschia pungens is a widely distributed marine pennate diatom. Hybrid zones, regions in which two different genotypes may interbreed, are important areas for speciation and ecology, and have been reported across the globe for this species. However, sexual reproduction between differing clades in the natural environment is yet to be observed and is difficult to predict. Here we carried out experiments using two mono-clonal cultures of P. pungens from different genotypes to measure the frequency and timing of sexual reproduction across varying biotic (growth phases and cell activity potential) and abiotic conditions (nutrients, light, turbulence). We found the mating rates and number of zygotes gradually decreased from exponential to late stationary growth phases. The maximum zygote abundance observed was 1,390 cells mL-1 and the maximum mating rate was 7.1%, both which occurred during the exponential growth phase. Conversely, only 9 cells mL-1 and a maximum mating rate of 0.1% was observed during the late stationary phase. We also found the higher the relative potential cell activity (rPCA) in parent cells, as determined by the concentration of chlorophyll a per cell and the ratio of colony formation during parent cultivations, revealed higher mating rates. Furthermore, sexual events were reduced under nutrient enrichment conditions, and mating pairs and zygotes were not formed under aphotic (dark) or shaking culture conditions (150 rpm). In order to understand the sexual reproduction of Pseudo-nitzschia in the natural environment, our results highlight that it is most likely the combination of both biotic (growth phase, Chl. a content) and abiotic factors (nutrients, light, turbulence) that will determine the successful union of intraspecific populations of P. pungens in any given region.
Water pollution due to plasticizers is one of the most severe environmental problems worldwide. Phthalate plasticizers can act as endocrine disruptors in vertebrates. In this study, we investigated whether the non-phthalate bis(2-ethylhexyl) sebacate (DEHS) plasticizer can act as an endocrine disruptor by evaluating changes in the expression levels of thyroid hormone-related, reproduction-related, and estrogen-responsive genes of Japanese medaka (Oryzias latipes) exposed to the plasticizer. Following the exposure, the gene expression levels of thyroid-stimulating hormone subunit beta (tshβ), deiodinase 1 (dio1), and thyroid hormone receptor alpha (trα) did not change. Meanwhile, DEHS suppressed dio2 expression, did not induce swim bladder inflation, and eventually reduced the swimming performance of Japanese medaka. These findings indicate that DEHS can potentially disrupt the thyroid hormone-related gene expression and metabolism of these fish. However, exposure to DEHS did not induce changes in the gene expression levels of kisspeptin 1 (kiss1), gonadotropin-releasing hormone (gnrh), follicle-stimulating hormone beta (fshβ), luteinizing hormone beta (lhβ), choriogenin H (chgH), and vitellogenin (vtg) in a dose-dependent manner. This is the first report providing evidence that DEHS can disrupt thyroid hormone-related metabolism in fish.
Spiders have emerged as one of the leading model organisms in many research fields due to their compelling biology. Often, scientific investigations involving the use of spiders face inevitable problems associated with the lack of specimens from laboratory stock, resulting in difficulties in yielding reproducible investigations for predictive research. Thus, several species of well-studied spiders, including Parasteatoda tepidariorum, have been successfully bred for such purposes. Crossopriza lyoni is a Haplogyne spider, globally distributed and widespread in human inhabitants, prompting interest in various studies over the last decades. Despite its scientific importance, no laboratory-bred C. lyoni has been documented. Therefore, we describe a successful captive breeding system of the species under controlled conditions to establish a laboratory stock culture. Methods for mating induction, egg collection and segregation, artificial embryo incubation, and colony husbandry are discussed. The technique presented is a simple and low-cost approach that is reliable for C. lyoni propagation in the laboratory over several generations.
In most livebearing fish, the gravid spot is an excellent marker to identify brooding females, however its use to predict progress of embryonic development, brood size, timing of parturition and overall reproductive potential of populations remain unexplored. Therefore, to understand these relationships, this study quantified visual attributes (intensity and size) of the gravid spot in relation to key internal development in Gambusia holbrooki. Observations show that the colour of the gravid spot arises from progressive melanisation on the surface of the ovarian sac at its hind margin, rather than melanisation of the developing embryos or the skin of the brooding mother. More importantly, the gravid spot intensity and size were closely linked with both developmental stages and clutch size, suggesting their reliable use as external surrogates of key internal developmental in the species. Using predictive consistency of the gravid spot, we also determined the effect of rearing temperature (23 °C and 25 °C) on gestation period and parturition behaviour. The results show that gestation period was significantly reduced (F = 364.58; df = 1,48; P ˃ 0.05) at 25 °C. However there was no significant difference in average number of fry parturated in the two temperature groups (P<0.05), reaffirming that gravid spot intensity is a reliable predictor of reproductive output. The parturition in the species occurred predominantly in the morning and in contrast to earlier reports, tails of the fry emerged first with a few exceptions of head-first, twin and premature births. This study demonstrates utility of the gravid spot for downstream reproductive investigations in a live-bearing fish both in the field and laboratory. The reproducibility of the relationships (intensity with both developmental stage and clutch size), imply that they are also relevant to wild populations that experience varying temperature climes and stressors, significant deviations of which may serve as indicators of environmental health and climate variability.
Primates, like other mammals, exhibit an annual reproductive pattern that ranges from strictly seasonal breeding to giving birth in all months of the year, but factors mediating this variation are not fully understood. We applied both a categorical description and quantitative measures of the birth peak breadth based on daily observations in zoos to characterise reproductive seasonality in 141 primate species with an average of 941 birth events per species. Absolute day length at the beginning of the mating season in seasonally reproducing species was not correlated between populations from natural habitats and zoos. The mid-point of latitudinal range was a major factor associated with reproductive seasonality, indicating a correlation with photoperiod. Gestation length, annual mean temperature, natural diet and Malagasy origin were other important factors associated with reproductive seasonality. Birth seasons were shorter with increasing latitude of geographical origin, corresponding to the decreasing length of the favourable season. Species with longer gestation periods were less seasonal than species with shorter ones, possibly because shorter gestation periods more easily facilitate the synchronisation of reproductive activity with annual cycles. Habitat conditions with higher mean annual temperature were also linked to less-seasonal reproduction, independently of the latitude effect. Species with a high percentage of leaves in their natural diet were generally non-seasonal, potentially because the availability of mature leaves is comparatively independent of seasons. Malagasy primates were more seasonal in their births than species from other regions. This might be due to the low resting metabolism of Malagasy primates, the comparatively high degree of temporal predictability of Malagasy ecosystems, or historical constraints peculiar to Malagasy primates. Latitudinal range showed a weaker but also significant association with reproductive seasonality. Amongst species with seasonal reproduction in their natural habitats, smaller primate species were more likely than larger species to shift to non-seasonal breeding in captivity. The percentage of species that changed their breeding pattern in zoos was higher in primates (30%) than in previous studies on Carnivora and Ruminantia (13 and 10%, respectively), reflecting a higher concentration of primate species in the tropics. When comparing only species that showed seasonal reproduction in natural habitats at absolute latitudes ≤11.75°, primates did not differ significantly from these two other taxa in the proportion of species that changed to a less-seasonal pattern in zoos. However, in this latitude range, natural populations of primates and Carnivora had a significantly higher proportion of seasonally reproducing species than Ruminantia, suggesting that in spite of their generally more flexible diets, both primates and Carnivora are more exposed to resource fluctuation than ruminants.
Activin A is a two-subunit protein belonging to the transforming growth factor β superfamily. First discovered almost three decades ago, it has since been implicated in diverse physiological roles, ranging from wound repair to reproduction. After 30 years of research, altered activin A levels are now understood to be associated with the development of various diseases, making activin A a potential therapeutic target. In pregnancy, the placenta and fetal membranes are major producers of activin A, with significantly enhanced serum concentrations now recognised as a contributor to numerous gestational disorders. Evidence now suggests that circulating levels of activin A may be clinically relevant in the early detection of pregnancy complications, including miscarriage and preeclampsia. This review aims to summarise our current understanding of activin A as a potential diagnostic marker in common pregnancy pathologies.
The present study examines genetic variation and correlated changes in reproductive performance traits in a red tilapia (Oreochromis spp.) population selected over three generations for improved growth. A total of 328 breeding females (offspring of 111 sires and 118 dams) had measurements of body weight prior to spawning (WBS), number of fry at hatching (NFH), total fry weight (TFW) and number of dead fry (NDF) or mortality of fry including unhatched eggs at hatching (MFH). Restricted maximum likelihood (REML) analysis in a multi-trait model showed that there are heritable genetic components for all traits studied. The heritability for WBS was very high (0.80). The estimates for traits related to fecundity (NFH, TFW) and survival (NDF) were low and they were associated with high standard errors. Genetic correlations of WBS with other reproductive performance traits (NFH, TFW and NDF) were generally positive. However, NFH was negatively correlated genetically with TFW. As expected, body measurements during growth stage exhibited strong positive genetic correlations with WBS. The genetic correlations between body traits and reproductive performance (NFH, TFW, NDF) were not significant. Correlated responses in reproductive traits were measured as changes in least squares means between generations or spawning years. Except for WBS that increased with the selection programs, the phenotypic changes in other reproductive traits observed were not statistically significant (P>0.05). It is concluded that the selection program for red tilapia has resulted in very little changes in reproductive performance of the animals after three generations. However, periodic monitoring of genetic changes in fecundity and fitness related traits such as NDF or MFH should be made in selective breeding programs for red tilapia.
We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh < or =70 cm. Fecundity parameters of individual trees per event varied widely (221,000-35,200,000 flowers, 0-139,000 mature seeds, and 1.04-177 kg total dry matter mass of fruit (TDM) per tree). Monotonic increases with increasing tree size were observed for flower production and TDM amongst trees up to 90 cm in dbh, but not for mature seed production or for any of these parameters amongst larger trees. The pattern of reproductive investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction.
A semi laboratory experiment using 3 cohorts of Aedes albopictus adults was performed to obtain age-specific mortality and fecundity information and to derive statistical estimates of some population growth parameters. Life expectancy was calculated for both males and females. The following population parameters were estimated: intrinsic rate of increase (rm= 0.21), net reproductive (replacement) rate (Ro= 68.70), age at mean cohort reproduction (To=10.55 days), birth rate (B=0.23), death rate (D=0.02) and generation time (G=20.14 days). The high rm/B (0.91) and B/D (11.50) ratios indicated the high colonizing ability of Ae. albopictus in nature.
A study was carried out to investigate correlation between presence of specific microalgal species and Leptoconops biting midge larvae in its breeding habitats. Sand samples containing microalgae were collected from the beach where the midges were most commonly biting and from sand beaches which are potential as breeding habitats of Leptoconops. The survey covered sand beaches from 12 seperate islands. At all sites, the Bacillariophyta constituted the largest representatives of the microalgae community with the majority from the Naviculaceae family. A total of 24 microalgal species were identified from the sand samples collected from the study sites. Sand samples from Kentot Kecil Island had the highest number of algal species (11.0) and the highest algae species diversity ( Shanon-Weiner Diversity Index, H' = 0.884). Besar Island (Johor) had the lowest number of algal species (2.0) whereas Tengol A Island had the lowest algae species diversity (H'=0.234). Highest similarity index was recorded between sand samples collected from Tengol A Island and Tengol B Island (75.0%) followed by Besar Island (Melaka) and Tengol B Island (62.0 %). The variation between other islands were relatively high. Virtually many kinds of algae were found where Leptoconops were breeding but Fragilaria intermedia, Mastigloia minuta and Navicula advena were particularly common.
Samples of threadfin breams Nemipterus japonicus were collected from a village in Kuala Nyalau and a fish landing centre at Bintulu from April 2013 to March 2014. A total of 360 individuals of N. japonicus (214 male and 146 female) were used in this reproductive study.? The total length (TL) of individuals were measured to the nearest 0.1 cm and body weight (BW) was recorded to the nearest 0.1 g. Month-wise distribution of the sexes was significantly higher for males in September and March, while in the month of May the number of females was significantly higher (X(2) = 6.53; P < 0.05). Males showed a preponderance in the size-class of 19.0-20.9 cm (X(2) = 80.24; P < 0.001), 21.0 -22.9 cm (X(2) = 56.39; P < 0.001) and 23.0 -24.9 cm (X(2) = 17; P < 0.001). The gonadosomatic index (GSI) values of N. japonicus ranged from 0.07 to 0.19 for males and 0.34 to 4.99 for females. Females had higher GSI than males throughout the study period. For males, a higher GSI (0.11-0.19) was observed during January to February, while it was found to be higher (2.73-4.99) for females during January to March, indicating the spawning season. The present study revealed that ovarian maturity based on histological analysis of N. japonicus was classified into seven stages namely, immature (I), immature (II), maturing (III), mature (IV), ripe (V), spawning (VI) and spent (VII). The fecundity of N. japonicus was estimated to be within a range of 19221 to 85923 with higher GSI (3.08-6.78) from the coastal waters of Bintulu, Sarawak.
Parapenaeopsis sculptilis (Heller, 1862) locally referred to as ?udang kulit keras? in Malaysia has profound biological, ecological, aquacultural and conservational significance. The reproductive biology of this important penaeid from the coastal waters of Perak, Peninsular Malaysia, was studied during the period between February 2012 to January 2013. Females outnumbered males with a sex ratio of M: F= 1:3 (P < 0.05). Four maturity stages of female gonads viz., immature, maturing, mature and spent stages were distinguished. The first stage of sexual maturity was attained at a length of 9.3 cm, and female P. sculptilis showed a peak gonadosomatic index during the month of April, August and October, indicating that P. sculptilis potentially breeds throughout the year. The findings of this study would greatly contribute towards the understanding of gonadal maturation, spawning season and breeding biology, which could be important for the effective population management of this prawn species.
The Sn atom in catena-poly[triphenyltin(IV)-micro-(3-ureidopropionato-O(1):O(3))], [Sn(C(6)H(5))(3)(C(4)H(7)N(2)O(3))](n), is five-coordinate and has a trans-C(3)SnO(2) trigonal-bipyrmidal geometry arising from bridging through the O atom of the ureido fragment of an adjacent carboxylate group. Infinite chains propagate helically along the c axis and adjacent chains are linked by N-H.O [N.O 2.851 (4) A] hydrogen bonds into layers.
In this overview, the authors have discussed the potential advantages of the association between mycorrhizae and plants, their mutual accelerated growth under favorable conditions and their role in nutrient supply. In addition, methods for isolating mycorrhizae are described and spore morphologies and their adaptation to various conditions are outlined. Further, the significant participation of controlled greenhouses and other supported physiological environments in propagating mycorrhizae is detailed. The reviewed information supports the lack of host- and niche-specificity by arbuscular mycorrhizae, indicating that these fungi are suitable for use in a wide range of ecological conditions and with propagules for direct reintroduction. Regarding their prospective uses, the extensive growth of endomycorrhizal fungi suggests it is suited for poor-quality and low-fertility soils.
In the title chalcone derivative, C15H9BrCl2O, the aryl rings are inclined to each by 14.49 (17)°, and the configuration about the C=C bond is E. There is a short intra-molecular C-H⋯Cl contact present resulting in the formation of an S(6) ring motif. In the crystal, the shortest inter-molecular contacts are Cl⋯O contacts [3.173 (3) Å] that link the mol-ecules to form a 21 helix propagating along the b-axis direction. The helices stack up the short crystallographic a axis, and are linked by offset π-π inter-actions [inter-centroid distance = 3.983 (1) Å], forming layers lying parallel to the ab plane. A qu-anti-fication of the inter-molecular contacts in the crystal were estimated using Hirshfeld surface analysis and two-dimensional fingerprint plots.
The dynamic of covid-19 epidemic model with a convex incidence rate is studied in this article. First, we formulate the model without control and study all the basic properties and results including local and global stability. We show the global stability of disease free equilibrium using the method of Lyapunov function theory while for disease endemic, we use the method of geometrical approach. Furthermore, we develop a model with suitable optimal control strategies. Our aim is to minimize the infection in the host population. In order to do this, we use two control variables. Moreover, sensitivity analysis complemented by simulations are performed to determine how changes in parameters affect the dynamical behavior of the system. Taking into account the central manifold theory the bifurcation analysis is also incorporated. The numerical simulations are performed in order to show the feasibility of the control strategy and effectiveness of the theoretical results.