Hasil untuk "Reproduction"

E. Besseling, Bo Wang, M. Lürling et al.

The amount of nano- and microplastic in the aquatic environment rises due to the industrial production of plastic and the degradation of plastic into smaller particles. Concerns have been raised about their incorporation into food webs. Little is known about the fate and effects of nanoplastic, especially for the freshwater environment. In this study, effects of nano-polystyrene (nano-PS) on the growth and photosynthesis of the green alga Scenedesmus obliquus and the growth, mortality, neonate production, and malformations of the zooplankter Daphnia magna were assessed. Nano-PS reduced population growth and reduced chlorophyll concentrations in the algae. Exposed Daphnia showed a reduced body size and severe alterations in reproduction. Numbers and body size of neonates were lower, while the number of neonate malformations among neonates rose to 68% of the individuals. These effects of nano-PS were observed between 0.22 and 103 mg nano-PS/L. Malformations occurred from 30 mg of nano-PS/L onward. Such plastic concentrations are much higher than presently reported for marine waters as well as freshwater, but may eventually occur in sediment pore waters. As far as we know, these results are the first to show that direct life history shifts in algae and Daphnia populations may occur as a result of exposure to nanoplastic.

J. Obeso

J. D. Neill, T. Plant, E. Knobil

J. Sterne

D. Hibbett, M. Binder, J. Bischoff et al.

T. Ashman, T. Knight, J. Steets et al.

G. Dawson

A. Agarwal, Sajal Gupta, R. Sharma et al.

Francesco Menegale, Mattia Manica, Martina Del Manso et al.

Abstract To address the growing frequency, extension, and size of local arboviral outbreaks in Europe we retrospectively analyzed dengue and chikungunya transmission in Italy from 2006 to 2023. We applied generalized additive models to the records of travel-related cases to highlight the spatiotemporal patterns of disease importation, calculated reproduction numbers for six local outbreaks based on autochthonous case data and mapped current transmission risks by applying a computational model that integrates human density, entomological, and climate data. Outbreak locations appear driven by case importation, which is notably higher for dengue – especially from June to October - rather than local transmission risks. Although reporting delays and favorable temperatures allowed onward transmission for several generations from mid-August to mid-November, upon outbreak detection control of transmission was achieved within 15 days. In high-risk areas, significantly longer epidemic risks were found for chikungunya (over 4 months). However, considering observed importation trends, increasingly frequent local dengue outbreaks are expected. Case detection should be prioritized focusing on areas, and in times, where environmental and climate conditions are permissive, regardless of prior outbreaks.

Bernd Faust

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Zeshan Faiz, Shumaila Javeed, Iftikhar Ahmed et al.

The major goal of this research study is to solve the fractional order Wolbachia invasive model (FWIM) by developing a computational framework based on the Bayesian regularization backpropagation neural network (BRB-NN) approach. The population of mosquitoes is categorized into two classes, Wolbachia-infected mosquitoes and Wolbachia-uninfected mosquitoes. We also incorporate incomplete cytoplasmic incompatibility and imperfect maternal transmission. We investigate the effects of the fractional order derivative (α) and reproduction rate of Wolbachia-infected mosquitoes ϕw on the dynamics of mosquitoes. The proposed Bayesian regularization backpropagation scheme is applied to three distinct cases using 80% and 20% of the created dataset for training and testing, respectively, with 15 hidden neurons. Comparisons of the results are presented to verify the validity of the proposed technique for solving the model. The Bayesian regularization approach is used to lower the mean square error (MSE) for the fractional order Wolbachia invasive model. The achieved results are based on MSE, correlation, state transitions, error histograms, and regression analysis to confirm the effectiveness of the suggested approach. Additionally, the absolute error value modifies the designed approach’s accuracy.

Dengyue Yuan, Junting Li, Siya Wang et al.

Body color is one of the most noticeable phenotypic and economic characteristics in fish. Fish exhibit a diverse array of body color mutations influenced by factors such as artificial selection and natural mutations. Elucidating the genetic mechanisms of these color variants in fish is crucial for developing new breeds with higher ornamental value. In this study, we identified a nonsense mutation in csf1ra (c. 1249 C>T) with whole genome resequencing technology, and which may potentially contribute to the albino phenotype in Channa asiatica. The albino individuals exhibited a substantial decrease in the expression level of csf1ra compared to that of the wild individuals. To unravel the underlying mechanism of csf1ra, we delved into comparative transcriptomic and gene expression analyses. Our findings suggest that csf1ra may impact tyrosine kinase activity. Furthermore, csf1ra may not only regulate the expression levels of genes (sox9, ephb6, and wnt9) involved in melanin-based pigmentation but also influence genes (ampd3, ak1, and bco1) associated with non-melanin-based pigmentation. Our study investigated the genetic basis of the albino mutant of C. asiatica and provided new insights into the function of csf1ra in fish pigmentation.

J. F. Silva, N. Ocarino, R. Serakides

H. Dobson, Robert Smith

Transport of post-partum cows or sheep before an oestradiol-induced LH surge delayed gonadotrophin secretion possibly by affecting hypothalamic activity but not via an opioid mediated mechanism as the effect could not be reversed by naloxone. In addition, reduced LH responses to GnRH were observed in cattle during transport. In sheep, adrenocorticotrophic hormone (ACTH) also diminished the LH response to GnRH, but only when GnRH was administered 3 h after ACTH, not after 0.5 h. This finding suggests that very early suppression of LH secretion by stressors is not mediated by ACTH action at the pituitary but that immediate activation of the sympathetic nervous system may be involved. In ewes during the breeding season, repeated exposure to GnRH at intervals of 2 h during transport resulted in lower LH responses to the second and third injections. When anoestrous ewes were treated with oestradiol and GnRH while being restrained and isolated, the onset of the LH surge was delayed. The effects of hypothalamus-pituitary-adrenal hyperactivity on LH release may involve suppression of GnRH receptor activity, a reduction in releasable LH, or both factors. Studies in vitro with perifused ovine pituitaries showed that ACTH or corticotrophin releasing hormone markedly suppressed LH secretion in response to the second of two exposures to GnRH. This occurred with pituitaries obtained from anoestrous ewes irrespective of prior treatment with oestradiol, suggesting that compounds from the hypothalamus-pituitary-adrenal do not exert effects on the oestradiol-sensitizing mechanisms on the pituitary. In conclusion, stressors affect reproductive function via actions at the hypothalamus as well as impairing pituitary LH release induced by GnRH.

Graeme B. Martin, S. W. Walkden-Brown

Changes in the nutrition of mature rams and goat bucks lead to profound responses in testicular size and therefore the rate of production of spermatozoa. These effects are largely due to changes in the size of the seminiferous tubules and in the efficiency of spermatogenesis. With the exception of severe undernutrition, the effects on spermatogenic function are not accompanied by similar changes in endocrine function of the testes, as measured by the production of testosterone or inhibin. In rams, moderate changes in nutrition affect gonadotrophin secretion for only a few weeks, whereas testicular growth is affected for several months. In mature male goats during the non-breeding season, nutrition-induced testicular growth does not seem to be associated with a gonadotrophin response. Such observations have led us to develop the hypothesis that nutrition-driven testicular growth is at least partly independent of changes in gonadotrophin secretion. The energetic components of the diet, rather than the protein content, seem to be responsible for affecting gonadotrophin secretion in rams. The volatile fatty acids, and not glucose, are the active factors, although intracerebral insulin may also play a role. Where these substrates act and whether they are also involved in the gonadotrophin-independent pathways requires testing. In conclusion, nutritional signals exert powerful effects on the reproductive system of mature male ruminants, and the responses are partly independent of changes in gonadotrophin secretion. In the gonads, the gametogenic tissue responds rapidly to changes in nutrition, but the endocrine compartments are less affected. Variations in the expression of the nutritional responses among sexes, breeds and species probably reflect variations in the role of this environmental factor as a modulator of reproductive function.

K. Duhig, L. Chappell, A. Shennan

Yu-Yan Li, Jun-Jie Chen, Meng-Yao Liu et al.

Improved knowledge on the regulation of reproductive diapause in Coccinella septempunctata, an important predator of aphids, is crucial for improving shelf-life and mass production of the ladybeetles. In many insects, the absence of juvenile hormone (JH) is a central regulator of reproductive diapause. JH is principally degraded by JH esterase (JHE) and JH epoxide hydrolase (JHEH). Previous studies have shown that genes encoding these enzymes were upregulated in early diapause of C. septempunctata, but whether increased JH degradation contributes to the reduction of JH levels and facilitates reproductive diapause remains unknown. Here, we investigate the role of JH and JH degradation genes during reproductive diapause in C. septempunctata females. Applying methoprene, a JH analogue, to the diapause preparation females clearly elevated JH signaling and reversed diapause program, suggesting that a lower level of JH is critical for the induction of reproductive diapause in the ladybeetle. Full-length cDNA sequences of JHE and JHEH were cloned and characterized, and their deduced proteins contain all the conserved active domains and typical motifs as identified in other insects. The expressions of JHE and JHEH were both significantly increased in diapause preparation and remained at a high level for a period throughout diapause, and then decreased after the termination of diapause. Knocking down these JH degradation genes clearly increased the expression levels of JH-inducible genes Krüppel-homolog 1 (Kr-h1) and vitellogenin (Vg), indicating an elevated JH level. Simultaneously, silencing JH degradation genes distinctly reduced diapause-related features and promotes reproduction, indicated by accelerated ovary growth, yolk deposition, and suppressed lipid accumulation. These results indicate that the enhanced JH degradation plays a critical role in regulating reproductive diapause of C. septempunctata.

Najmul Haider, Javier Guitian, David Simons et al.

We explain research gaps on Monkeypox (MPX) virus epidemiology in endemic countries and present hypotheses for the recent increase of MPX cases in West Africa as a possible explanation for the current epidemic in Europe, America, and Australia. The detection of >400 MPX cases in less than a month in May 2022, across many countries underscores the epidemic potential of MPX in humans and demonstrates several important research gaps. First, the true burden of MPX in West and Central Africa is poorly understood, although it is critical for prevention and control of future outbreaks. Second, the diversity and extent of the animal reservoir remain unknown. We hypothesize that the synanthropic rodent population has increased in recent years in Africa leading to more human-rodent interactions and thus increased transmission of MPXV. We further hypothesise that nearly 45 years after the end of routine smallpox vaccination, the larger and more interconnected immune-naïve population has crossed a threshold resulting in more sustainable human-to-human transmission of MPXV. The current epidemic in the Western World is possibly a consequence of increased local transmission of MPXV in Africa. A new estimation of the basic and effective reproduction rate (R0 and Re) in different populations is required. National, regional, and international collaborations are needed to address research gaps related to MPX outbreaks.

Yu-Ke Liu, Guo-Hua Liu, Lei Liu et al.

Abstract Background Haemaphysalis flava is a hematophagous ectoparasite that acquires the nutrition needed for development and reproduction by sucking blood and digesting the blood meal. During blood-sucking and blood-meal digestion, the prevention of blood coagulation is important for this tick. Previous studies have shown that heat shock cognate 70 (HSC70) protein has certain anticoagulant activities, but its immunogenicity remains unclear. Also, whether the mutation of individual bases of the TKD-like peptide of HSC70 through the overlap extension method can change its anticoagulant activities and immunogenicity remains to be investigated. Methods The gene encoding the HSC70 protein was cloned from a complementary DNA library synthesized from H. flava. The coding gene of the TKD-like peptide of HSC70 was mutated into a TKD peptide coding gene (HSC70TKD) using the overlap extension method. Escherichia coli prokaryotic expression plasmids were constructed to obtain the recombinant proteins of HSC70 (rHSC70) and HSC70TKD (rHSC70TKD). The purified rHSC70 and rHSC70TKD were evaluated at different concentrations for anticoagulant activities using four in vitro clotting assays. Emulsifying recombinant proteins with complete and incomplete Freund’s adjuvants were subcutaneously immunized in Sprague Dawley rats. The serum antibody titers and serum concentrations of interferon-gamma (IFN-γ) and interleukin-4 (IL-4) were detected using an indirect enzyme-linked immunosorbent assay to assess the immunogenicity of rHSC70 and rHSC70TKD. Results The open reading frame of HSC70 was successfully amplified and found to have a length of 1958 bp. The gene encoding the TKD-like peptide of HSC70 was artificially mutated, with the 1373-position adenine (A) of the original sequence mutated into guanine (G), the 1385-position cytosine (C) mutated into G and the 1386-position G mutated into C. rHSC70 and rHSC70TKD that fused with His-tag were obtained using the expression plasmids pET-28a-HSC70 and pET-28a-HSC70TKD, respectively. rHSC70 and rHSC70TKD prolonged the thrombin time (TT) and reduced the fibrinogen (FIB) content in the plasma, but did not affect the prothrombin time (PT) or activated partial thromboplastin time (APTT) when compared to the negative control. Interestingly, the ability of rHSC70TKD to prolong the TT and reduce the FIB content in the plasma was better than that of rHSC70. The specific antibody titers of both rHSC70 and rHSC70TKD in rat serum reached 1:124,000 14 days after the third immunization. The serum concentration of IFN-γ in the rHSC70TKD group was higher than that in the rHSC70 group. The rHSC70 group has the highest serum concentration of IL-4, and the serum concentration of IL-4 in the rHSC70TKD group was higher than that in the negative group. Conclusions rHSC70 and rHSC70TKD exhibited anticoagulant activities by prolonging the TT and reducing the FIB content in vitro. rHSC70TKD had better anticoagulant activities than rHSC70. Both rHSC70 and rHSC70TKD had good immunogenicity and induced humoral and cellular immunity.

A. Hacket‐Pain, D. Ascoli, G. Vacchiano et al.

Abstract Climatically controlled allocation to reproduction is a key mechanism by which climate influences tree growth and may explain lagged correlations between climate and growth. We used continent‐wide datasets of tree‐ring chronologies and annual reproductive effort in Fagus sylvatica from 1901 to 2015 to characterise relationships between climate, reproduction and growth. Results highlight that variable allocation to reproduction is a key factor for growth in this species, and that high reproductive effort (‘mast years’) is associated with stem growth reduction. Additionally, high reproductive effort is associated with previous summer temperature, creating lagged climate effects on growth. Consequently, understanding growth variability in forest ecosystems requires the incorporation of reproduction, which can be highly variable. Our results suggest that future response of growth dynamics to climate change in this species will be strongly influenced by the response of reproduction.