Neuromuscular and vascular hamartoma of the small intestine in an F344 rat

An intestinal mass was found in the border area of the jejunum and ileum of a 110-week-old male F344 rat. Histopathologically, the mass protruded into the lumen and was covered with intestinal epithelium, exhibiting a normal architecture. The lesion was located in the submucosa and consisted of loose connective tissue, smooth muscle, scattered ganglion cells, and blood vessels of various sizes. Although these components showed an irregular and disordered structure, no cellular atypia, increased proliferation activity, or invasive growth to adjacent tissues were detected. Immunohistochemical analyses revealed that smooth muscle, ganglion, and endothelial cells were positive for α-smooth muscle actin and vimentin, S-100, and CD34 and von Willebrand factor, respectively, indicating maturation of these cells. Thus, the mass was diagnosed as a neuromuscular and vascular hamartoma of the small intestine. To the best of our knowledge, this is the first report of this type of lesion in rodents.     

The canine RAD51 mutation leads to the attenuation of interaction with PALB2

RAD51 forms a complex with BRCA2 and plays a central role in the DNA damage response pathway that is associated with homologous recombination. The structures of RAD51 and its homologues are highly conserved from prokaryotes to higher eukaryotes. Although a large number of BRCA2 mutations have been reported, there are only a few reports on the mutations of RAD51, which have been shown in humans and dogs. However, several mutations of canine RAD51 were identified from mammary gland tumour tissues in a recent study. Some of these mutations seem to have an influence on the homo‐oligomerization or interaction with “Partner and localizer of BRCA2” (PALB2). In this study, we cloned the canine PALB2 homologue and investigated the effect on its interaction with the RAD51 mutants to evaluate the alteration in the function of RAD51 mutants. The A209S and T225S mutants of RAD51 show an attenuation of the interaction between RAD51 and PALB2. These results indicate that the canine RAD51 mutations can potentially alter the homologous recombination pathways in response to DNA damage in dogs.     

Mixed Type of Malignant Mesothelioma in an Aged Male ICR Mouse

Multiple whitish nodules in the thoracic cavity at the site of the thymus were observed in a 101-week-old male ICR mouse. In a histopathological examination, the neoplastic cells were predominantly fusiform in shape and proliferated in sarcomatoid growth patterns. Some neoplastic cells showed epithelial growth patterns, such as the ductal structures. Mitotic figures were frequently seen, and small necrotic foci and invasion to adjacent thoracic organs were noted. In Alcian blue staining, bluish materials were observed between fusiform-shaped cells and in some of the lumens of the ductal structures. In immunohistochemistry, both fusiform-shaped and ductal structure-forming cells were positive for vimentin and weakly positive to positive for cytokeratin. Based on the aforementioned findings, the thoracic nodules were diagnosed as a mixed type of malignant mesothelioma. This case was thought to be rare because of the very low occurrence of spontaneous mesothelioma in mice.     

Analyses of the regulatory mechanism of porcine WEE1B: the phosphorylation sites of porcine WEE1B and mouse WEE1B are different

WEE1B, an oocyte-specific kinase, phosphorylates the CDC2 inhibitory site and maintains the meiotic arrest of oocytes at the first meiotic prophase in several mammalian species. However, the molecular mechanisms controlling WEE1B activity have not been fully examined in species other than mice. In the present study, we analyzed the regulation mechanisms of porcine WEE1B (pWEE1B), focusing on the cAMP-dependent protein kinase (PKA) phosphorylation site and intracellular localization. As the PKA phosphorylation site in mouse WEE1B (mWEE1B) was not conserved in pWEE1B, we predicted that four serine residues would be phosphorylatable by PKA in pWEE1B (Ser77, Ser118, Ser133 and Ser149) and constructed FLAG-tagged replaced-pWEE1Bs, in which each of the PKA-phosphorylatable serines was mutated into a non-phosphorylatable alanine. We injected one of their mRNAs into porcine immature oocytes and found that the Ser77-replaced pWEE1B lost the WEE1B function, whereas the wild-type and other replaced-pWEE1Bs could maintain the meiotic arrest of oocytes. Next, the localization of pWEE1B was examined by immunohistochemistry, and exclusive nuclear localization was revealed in the fully grown oocytes. We generated a nuclear localization signal (NLS)-deleted pWEE1B (ΔNLS-pWEE1B) and then overexpressed it in porcine immature oocytes. We found that ΔNLS-pWEE1B was distributed uniformly in the cytoplasm and could not maintain the meiotic arrest of porcine oocytes. These results suggest that pWEE1B is activated after phosphorylation of the Ser77 residue, which is different from the phosphorylation site that activates mWEE1B; that pWEE1B is localized in the nucleus; and that the nuclear localization is essential for its function.     

Japanese consumer categorisation of beef into quality grades,based on Meat Standards Australia methodology

The objective was to evaluate the sensory categorisation of beef by Japanese consumers, based on Meat Standards Australia methodology. Various cuts of beef, with a wide range of quality (from Australian and Japanese cattle) and three cooking methods (grill, yakiniku, shabu shabu), were evaluated by 1620 Japanese consumers in Tokyo and Osaka. Consumers rated each sample for four sensory attributes (tenderness, juiciness, flavor and overall satisfaction), then selected one of four grades (unsatisfactory/2‐star, good everyday/3‐star, better than everyday/4‐star, and premium quality/5‐star), based on the quality of the beef within each cooking method. Meat quality scores, denoted as MQ4 scores (weighted combination of the four sensory attributes) were calculated from the Japanese consumer test results, to describe the Japanese consumer rating of beef. The distribution of the Japanese consumer MQ4 scores showed a clear distinction between grades, with the majority of scores being included within the boundaries of each grade. The MQ4 score allocated approximately 64% of the samples to their correct consumer grades. The MQ4 score showed potential to be used as a tool in developing and monitoring a consumer‐focused grading system that is able to predict Japanese consumer satisfaction of individual beef cuts prepared by different cooking methods.     

Ammonium uptake capacity and response of cytosolic glutamine synthetase 1;2 to ammonium supply are key factors for the adaptation of ammonium nutrition in Arabidopsis thaliana

Plant requires nitrogen for the growth, and it use nitrate and ammonium from the environment. Plant suffers from the toxicity when excess ammonium is supplied as a sole nitrogen, although it could be a good nitrogen source for plant growth. We hypothesized that the different responses of ecotypes to ammonium nutrient could partly account for the adaptation of Arabidopsis to an ammonium environment. The purpose of this study is to understand the different responses of ecotypes in ammonium environment. The growth of Arabidopsis thaliana ecotypes, Columbia was compared to those of Arabidopsis thaliana ecotypes, Landsberg erecta in ammonium nutrient. The ratio of shoot dry weight to root dry weight was compared to evaluate the adaptation of two ecotypes. The shoot:root ratio of Landsberg was significantly higher than that of Columbia. T-DNA insertion in cytosolic glutamine synthetase 1;2, one of the essential ammonium assimilatory enzymes, led a decrease of shoot:root ratio. We also measured the isotope-labeled ammonium uptake and the expression levels of ammonium transporter genes, and also the expression of ammonium assimilatory genes, glutamine synthetase genes and glutamate synthase genes, in roots after ammonium re-supply using real-time polymerase chain reaction analysis. We found that (1) ammonium uptake of Landsberg erecta was higher than that of Columbia, when ammonium was supplied at higher concentration, and (2) cytosolic glutamine synthetase 1;2 was highly increased by ammonium supply in the root of Landsberg erecta. The present study suggested the importance of these two factors for adaptation of Arabidopsis to an ammonium-rich environment.     

Natural hybridization between <Emphasis Type="Italic">Pinctada fucata</Emphasis> and <Emphasis Type="Italic">Pinctada maculata</Emphasis> inferred from internal transcribed spacer regions of nuclear ribosomal RNA genes

ABSTRACT:   Genetic evidence of the occurrence of natural hybridization between female Pinctada fucata and male Pinctada maculata among wild pearl oysters ( n  = 20) collected for use as the mother shell for private pearl farming in the Oshima Strait at Amami-o-shima, Kagoshima Prefecture, Japan, were obtained. A polymerase chain reaction-based species identification method for Pinctada was developed using polymorphisms in the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA (rRNA) gene. This method enabled the amplification of the ITS regions using a primer set specific for P. maculata and P. fucata . However, 10 of 20 individuals morphologically identified as P. fucata had sequences specific to both P. maculata and P. fucata in the ITS region. These putative hybrids showed sequences of a maternally inherited mitochondrial 16S rRNA gene, identical to that of P. fucata . Shells of the putative hybrids were difficult to discriminate from those of P. fucata exhibiting similar taxonomic traits. Moreover, the hybrids exhibited slower growth than P. fucata but faster growth than P. maculata .     

Decorin activates Akt downstream of IGF‐IR and promotes myoblast differentiation

Decorin, a small leucine‐rich proteoglycan, plays an important role in cellular activities through modification of growth factors. It also acts as a signaling molecule to non‐muscle cells through epidermal growth factor receptor or insulin‐like growth factor I receptor (IGF‐IR). However, it is unclear if decorin acts as a signaling molecule to myogenic cells. In this study, we investigated the effect of decorin on the differentiation of myoblasts and the signaling via IGF‐IR to myogenic cells. C2C12 myoblasts cultured in media containing decorin for 72 h showed more extensive formation of multinucleated myotubes than control cells cultured in the same media without decorin. The protein expressions of myogenin and myosin heavy chian were higher in decorn‐treated cells than in control cells. These results suggest that decorin enhances the differentiation of myoblasts. Western blot analysis and immunocytochemistry showed that IGF‐IR was expressed in myoblasts and myotubes. Furthermore, Akt, which is downstream of IGF‐IR, was more phosphorylated in myoblasts cultured in media containing decorin than those in media without decorin. These results suggest that decorin activates Akt downstream of IGF‐IR and enhances the differentiation of myogenic cells.     

The role of intramuscular connective tissue in meat texture

The structure, composition and amount of intramuscular connective tissue (IMCT) vary tremendously between muscles, species and breeds, and certainly contribute to meat texture. With animal growth, collagen crosslinks become more stable, and the structural integrity of IMCT increases. These changes increase the mechanical properties of IMCT, contributing to the toughening of meat. Intramuscular fat deposits, mainly in the perimysium between muscle fiber bundles, result in marbling. This causes the remodeling of IMCT structures and reduces the mechanical strength of IMCT, contributing to the tenderization of beef. The IMCT has been thought to be rather immutable compared to myofibrils during postmortem ageing of meat. However, recent studies have shown the disintegration of IMCT during postmortem ageing of meat and its relationship to tenderization of raw meat, although its contribution to cooked meat is still controversial. Given the large influence of IMCT on meat texture, further elucidations of molecular mechanisms which change the structural integrity of IMCT during chronological ageing of animals and postmortem ageing of meat are needed.