Regulation of root-to-leaf Na and Cl transport and its association with photosynthetic activity in salt-tolerant soybean genotypes

ABSTRACT

Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO₂ assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO₂ concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding.     

Genetic relationship of body measurement traits at early age with carcass traits in Japanese black cattle

Estimates of genetic parameters were obtained for body measurement traits of 648 animals at 4 months of age, of 545 at 8 months and carcass traits of 14 972 animals with the use of an animal model by the restricted maximum likelihood procedure. The estimated heritabilities for carcass traits were high (0.41 to 0.54). At 4 months the estimated direct heritabilities for body measurement traits were moderate to high (0.28 to 0.64), except for chest width (0.19); at 8 months they were also moderate to high (0.23 to 0.49), except for chest depth and chest width (0.18 and 0.06, respectively). Maternal heritabilities for all body measurement traits were low at both ages. The results indicate that because of their moderate direct genetic correlations with body measurement traits, carcass weight, rib thickness and subcutaneous fat thickness can be improved; however, rib eye area and beef marbling standard show little such possibility considering their correlation with body measurement traits.     

Seasonality of serum levels of vitellogenin in male Japanese whiting, Sillago japonica, reared under natural temperature and photoperiod

ABSTRACT:   Because blood vitellogenin (Vg) has been considered a biomarker for environmental estrogens, the basal levels of Vg and 17β-estradiol (E₂) were determined in male Japanese whiting reared under natural conditions. Serum levels of Vg and E₂ were measured and gonadal development was assessed by gonadosomatic index (GSI) and histological observation in 8–10 male fish at monthly intervals throughout the annual reproductive cycle. Serum E₂ was <60 pg/mL throughout the study period. In contrast, serum Vg exhibited seasonal changes: serum levels of Vg gradually increased from April to May (mean 63 ± 13 ng/mL and 124 ± 48 ng/mL in April and May, respectively), and then reached a peak value (mean 352 ± 68 ng/mL) in June. Thereafter, serum Vg gradually decreased, reaching undetectable levels (<50 ng/mL) in October. Serum levels of Vg tended to increase in the male fish in which the GSI was >1%. Histological observation revealed that testes in such male fish were in active spermatogenesis and then all of the testes of male fish in which serum Vg decreased to ND levels were regressed. These results suggest that Vg productive potency (sensitivity to estrogens) may increase in the spermatogenic stage, resulting in production of Vg in response to very low levels of natural or xenobiotic estrogens.     

Generation of PDX‐1 mutant porcine blastocysts by introducing CRISPR/Cas9‐system into porcine zygotes via electroporation

Recently, we established the GEEP (“gene editing by electroporation of Cas9 protein”) method, in which the CRISPR/Cas9 system, consisting of a Cas9 protein and single guide RNA (sgRNA), is introduced into pig zygotes by electroporation and thus induces highly efficient targeted gene disruption. In this study, we examined the effects of sgRNA on the blastocyst formation of porcine embryos and evaluated their genome‐editing efficiency. To produce an animal model for diabetes, we targeted PDX‐1 (pancreas duodenum homeobox 1), a gene that is crucial for pancreas development during the fetal period and whose monoallelic disruption impairs insulin secretion. First, Cas9 protein with different sgRNAs that targeted distinct sites in the PDX‐1 exon 1 was introduced into in vitro‐fertilized zygotes by the GEEP method. Of the six sgRNAs tested, three sgRNAs (sgRNA1, 2, and 3) successfully modified PDX‐1 gene. The blastocyst formation rate of zygotes edited with sgRNA3 was significantly (p < 0.05) lower than that of control zygotes without the electroporation treatment. Our study indicates that the GEEP method can be successfully used to generate PDX‐1 mutant blastocysts, but the development and the efficiency of editing the genome of zygotes may be affected by the sgRNA used for CRISPR/Cas9 system.     

Relationship among ovarian follicular status,developmental competence of oocytes,and anti‐Müllerian hormone levels: A comparative study in Japanese wild boar crossbred gilts and Large White gilts

The aim of this study was to investigate the ovarian follicular development, developmental competence of oocytes, and plasma anti‐Müllerian hormone (AMH) levels of Japanese wild boar crossbred (wild hybrid) gilts, whose litter size is inferior to that of European breeds. Ovary and plasma samples were collected from two different breeds of gilts (wild hybrid and Large White breeds). The ovaries from the wild hybrid gilts had a lower average numbers of secondary follicles and vesicular follicles in ovarian cross‐sections and of good quality oocytes collected from ovarian follicles as compared with those from Large White gilts (p < 0.05). The development rate to the blastocyst stage of good quality oocytes after in vitro maturation, fertilization and culture was also lower (p < 0.05) in wild hybrid gilts than in Large White gilts. Plasma AMH levels with >0.16 ng/ml were detected in 8.3% of the examined wild hybrid gilts and 33% of the Large White gilts. These results indicate that the low reproductive performance of wild hybrid breed may result in part from low numbers of vesicular follicles and good quality oocytes, and low developmental competence of oocytes. Moreover, plasma AMH levels may support low number of vesicular follicles in ovaries of wild hybrid gilts.     

Genetic and biological characterization of feline foamy virus isolated from a leopard cat (Prionailurus bengalensis) in Vietnam

Foamy viruses have been isolated from various mammals and show long-term co-speciation with their hosts. However, the frequent inter-species transmission of feline foamy viruses (FFVs) from domestic cats to wild cats across genera has been reported. Because infectious molecular clones of FFVs derived from wild cats have not been available, whether there are specific characteristics enabling FFVs to adapt to the new host species is still unknown. Here, we obtained the complete genome sequences of two FFV isolates (strains NV138 and SV201) from leopard cats (Prionailurus bengalensis) in Vietnam and constructed an infectious molecular clone, named pLC960, from strain NV138. The growth kinetics of the virus derived from pLC960 were comparable to those of other FFVs derived from domestic cats. Phylogenetic analysis revealed that these two FFVs from leopard cats are clustered in the same clade as FFVs from domestic cats in Vietnam. Comparisons of the amino acid sequences of Env and Bet proteins showed more than 97% identity among samples and no specific amino acid substitutions between FFVs from domestic cats and ones from leopard cats. These results indicate the absence of genetic constraint of FFVs for interspecies transmission from domestic cats to leopard cats.     

Clinicopathological features of canine neuroaxonal dystrophy and cerebellar cortical abiotrophy in Papillon and Papillon-related dogs

Neuroaxonal dystrophy (NAD) was examined in two Papillon dogs and a mix breed dog between Papillon and Chihuahua. In addition, cerebellar cortical abiotrophy (CCA) in a Papillon dog, which had similar clinical and magnetic resonance imaging (MRI) features to those of NAD, was also investigated. The common clinical symptoms of all dogs affected with NAD and CCA, were pelvic limb ataxia and cerebellar ataxia including intention tremor, head tremor, and hypermetria in the early onset. These clinical signs were progressed rapidly, and two dogs with NAD were euthanized by owner's request and the other two died by aspiration pneumonia. MRI examinations and gross observations at necropsy revealed moderate to severe cerebellar atrophy in all cases of NAD and CCA. The most typical histological change of NAD was severe axonal degeneration with marked spheroid-formation in the dorsal horn of the spinal cords, the nuclei gracilis, cuneatus, olivalis and its circumference in the medulla oblongata. The spheroids were characterized as large eosinophilic or granular globes within the enlarged myelin sheaths, sometimes accompanied by moderate accumulation of microglias and/or macrophages. In contrast, such spheroid formation was minimal in the brain of CCA. In the cerebellum, mild to moderate loss of the Purkinje and granular cells were recognized in three dogs with NAD, whereas these changes were more prominent in a dog with CCA. Although the clinical signs and MRI findings relatively resembled between NAD and CCA, the histopathological features considered to be quite differ, suggesting distinct pathogenesis and etiology. Since both NAD and CCA are proposed as the autosomal recessive hereditary disorders, careful considerations might be needed for the breeding of Papillon and Chihuahua dogs.     

Congenital cutaneous fibropapillomatosis without evidences of papillomavirus infection in a Holstein-Friesian calf

A male Holstein-Friesian calf was born with multiple, cauliflower-like, pale pink cutaneous masses on the head and limbs. On histopathological examination, the cutaneous masses were diagnosed as congenital cutaneous fibropapillomatosis. Those lesions involved focal proliferation of sebaceous gland in the dermis. There were no histological findings to suggest bovine papillomavirus infection, such as the presence of intranuclear inclusion bodies, large keratohyalin granules, and koilocytosis. Furthermore, papillomaviral antigens and DNA were not detected by immunohistochemistry and polymerase chain reaction, respectively. These results suggested that there was no association between these cutaneous lesions and bovine papillomavirus infection, and the lesions were considered as harmartomatous changes.     

Toxicity and absorption of dietary leucomalachite green in Nile tilapia Oreochromis niloticus

Farmed fish are exposed to risks from feed-borne chemical contamination, such as leucomalachite green (LMG) in fish meal. Consequently, the use of malachite green is prohibited in aquacultural practice. An improved understanding of the toxicity of dietary LMG provided to farmed fish is needed in order to manage risk. Oreochromis niloticus specimens were fed experimental diets containing 0, 100, 500, and 2500 μg/kg LMG for 28 days. On sampling days 7, 14, and 28, fish in the exposed groups had detectable levels of LMG. Accumulation levels were approximately 12.2 % (in the liver) and 6.2 % (in the muscle) of the LMG concentration in the feed (104, 510, and 2200 μg/kg). Hematocrit and mean corpuscular hemoglobin concentrations in the 500 and 2500 μg/kg groups were significantly elevated at 7 and 14 days. Hemoglobin in the group that received the highest dose was significantly higher than that in the control group. Significant increases in the activities of alanine aminotransferase and alkaline phosphatase were also detected in the group receiving the highest dose. Total cholesterol concentrations in all of the exposed groups were significantly higher than those in the control group. These observations of toxicity were dose dependent. Histological changes in gills and livers were observed in LMG-exposed fish.