Progression of the dose-related effects of estrogenic endocrine disruptors, an important factor in declining fertility, differs between the hypothalamo-pituitary axis and reproductive organs of male mice

For the purpose of investigation of working mechanisms in endocrine disruptors, we evaluated the dose-related effects of fetal and/or neonatal exposure to an estrogenic compound on the male reproductive organs in adult mice, particularly with respect to gene expression of steroidogenic acute regulatory protein (StAR). The pregnant ICR mice were given subcutaneous injections of 10 micro g/day/animal of diethylstilbestrol (DES) to subject the fetal mice to in utero exposure (IUE). Subsequently, the newborn male mice were subjected to neonatal exposure (NE) by treatment with vehicle or 0.1-10 micro g/day/animal of DES. Fertility rates of each group were as follows: control, 100%; IUE only, 60%; IUE+NE 0.1 micro g, 25%; IUE+NE 1 micro g, 0%; IUE+NE 10 micro g, 0%. In general histology, germ cell layers in the seminiferous tubules were thinned in the group of IUE+NE 10 micro g. Hypoplasia of the Leydig cells, in which the staining intensity of eosin was diminished, was also observed in the groups of IUE+NE 0.1-10 micro g. The androgen receptor (AR) and estrogen receptor alpha (ERalpha) immunoexpression in the Leydig cells of IUE+NE 1-10 micro g was slightly lower than that in the controls. Long-term dysfunction of the hypothalamo-pituitary-testicular axis, including sustained hypoproduction of gonadotropin and testosterone, and altered expressions of steroid hormone receptors and StAR genes were observed. The hypothalamo-pituitary control of gonadotropin secretion may be affected by the smaller doses of estrogenic agents than the reproductive organs. Furthermore, the fertility rate in the male mice exposed to this estrogenic agent was closely correlated with the testosterone levels, and even more so with the rate-limiting factor of steroidogenesis, StAR. This finding suggests that endocrine disruptors have an important pronounced effect on StAR gene expression.     

The influence of increased water temperature on the duration of spermatogenesis in a neotropical fish,Astyanax altiparanae (Characiformes,Characidae)

Fish Physiology and Biochemistry - In view of the established climate change scenario and the consequent changes in global temperature, it is essential to study its effects on animal...     

Lactococcus garvieae outbreaks in Brazilian farms Lactococcosis in Pseudoplatystoma sp. – development of an autogenous vaccine as a control strategy

This study evaluated the control of streptococcosis outbreaks in Brazil, isolated from diseased sorubim and identified as Lactococcus garvieae by genetic sequencing. This report determined the potential for lactococcosis control in sorubim Pseudoplatystoma sp. with two vaccines: an aqueous‐based, whole‐cell inactivated vaccine (bacterin) and an oil‐adjuvanted bacterin. Their efficacy was evaluated at 30 days post‐vaccination (d.p.v.) by challenge with L. garvieae, and the antibody production response at 15, 30 and 60 d.p.v. and the non‐specific immune response were compared amongst treatments. High protection levels (P < 0.05) were achieved with the oil‐adjuvanted vaccine with a relative percentage survival value of 81.7% at 30 d.p.v. Additionally, the oil‐adjuvanted vaccine increased the immunogenicity of the bacterin as indicated by greater agglutination antibody titres from 15 until 60 d.p.v. This is the first report of a positive effect of vaccine administration on the specific immunity of sorubim, and the study showed that a specific antibody plays an important role in sorubim defence against lactococcosis because the innate immune responses were similar in all of the studied animals. These results demonstrated that oil‐adjuvanted vaccine can be an effective alternative for the protection of sorubim from L. garvieae disease.     

Molecular mapping of Asian soybean rust resistance in soybean landraces PI 594767A,PI 587905 and PI 416764

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is one of the most serious diseases of soybean. The soybean landraces PI 594767A, PI 587905 and PI 416764 previously showed high levels of resistance to a wide range of ASR fungus, while the genetic basis of the resistance has yet to be understood. In this study, the ASR resistance loci were mapped using three independent mapping populations, POP‐1, POP‐2 and POP‐3 derived from crosses BRS184 × PI 594767A, BRS184 ×  PI 587905 and BRS184 × PI 416764, respectively. In each population, the resistance to ASR segregated as a single gene, but the resistance was dominant in PI 594767A and PI 587905 and incompletely dominant in PI 416764. The resistance genes from both PI 594767A and PI 587905 were mapped on chromosome 18 corresponding to the same location as known resistance locus Rpp1. Quantitative trait locus (QTL) analysis performed on POP‐3 identified the putative ASR resistance locus in PI 416764 on the defined region of chromosome 6 where Rpp3 was located. The QTLs detected by the mapping explained about 67–72% of the phenotypic variation in POP‐3. Cluster analysis based on disease reactions to 64 ASR populations demonstrated the presence of at least two types of functional resistant Rpp1 alleles: strong and weak allele(s), e.g. soybean accession PI 594767A and PI 587905 carry the strong resistant Rpp1 allele(s). Introducing or pyramiding strong Rpp1 allele(s) in elite soybean cultivars is expected to be useful against the South American rust population.     

A tetraploid Echinochloa with plagiotropic tillers: Its distribution and habitat in the northern part of the main island of Japan

An annual Echinochloa with plagiotropic tillers (semi‐erect type) was found on a paddy levee in Miyagi prefecture in Japan. This semi‐erect type had tetraploid chromosome numbers (2n = 36) and would be expected to be E. oryzicola. However, its appearance was distinct from that of E. oryzicola. To collect seed samples and clarify its distribution and habitat, exploration and collection surveys were carried out in the northern part of Honshu, the main island of Japan in 2014, 2017, and 2018. Thirty‐two populations that were assumed to be the semi‐erect type were found and their mature seeds were collected. Based on the results of chromosome counts and growth form analyses, all of them were confirmed to be the semi‐erect type. The 32 populations were distributed in the prefectures of Aomori, Iwate, Akita, Miyagi, Yamagata, Fukushima, and Niigata, and located in paddy fields, abandoned paddy fields, paddy levees, roadsides, vacant land, and scree slopes. Our surveys indicated that the semi‐erect type grew in wet and dry disturbed habitats at an early stage of secondary succession including paddy fields in the northern part of the main island of Japan.