Involvement of histone H2B monoubiquitination in the regulation of mouse preimplantation development

Histone H2B monoubiquitination (H2Bub1) plays an important role in developmental regulation in various vertebrate species. However, the role of H2Bub1 in mammalian preimplantation development remains unclear. In the present study, we examined the role of H2Bub1 in the regulation of mouse preimplantation development. Based on immunocytochemical analysis using an anti-H2Bub1 antibody, no H2Bub1 signal was detected in the metaphase chromosomes of unfertilized oocytes or the pronuclei of early 1-cell stage embryos, but a weak signal was observed in late 1-cell stage embryos. The signal increased after cleavage into the 2-cell stage, and thereafter a strong signal was observed until the blastocyst stage. To assess the significance of H2Bub1 in the regulation of preimplantation development, RNF20 (an H2B-specific ubiquitin E3 ligase) was knocked down using small interfering RNA (siRNAs). In embryos treated with siRNA, the levels of Rnf20 mRNA and H2Bub1 decreased at the 4-cell and morula stages. Although these embryos developed normally until the morula stage, only one-third developed into the blastocyst stage. These results suggested that H2Bub1 is involved in the regulation of preimplantation development.     

Arteriovenous shunts resembling patent ductus arteriosus in dogs: 3 cases

Three dogs presented for the evaluation of cardiac murmurs were diagnosed with aberrant arteriovenous shunts. All cases demonstrated the following findings: 1) relatively soft continuous murmur loudest at the left heart base resembling patent ductus arteriosus (PDA); 2) shunt flow signals in the pulmonary artery on echocardiography; and 3) no PDA on selective angiography, but evidence of anomalous shunting vessels from thoracic aorta to pulmonary vasculature. An aberrant arteriovenous shunt should be considered when a continuous murmur of relatively small intensity is heard.     

Evaluation of three phytoplankton species as food for the pearl oyster <Emphasis Type="Italic">Pinctada fucata</Emphasis>

In the pearl cultivation farms of the Ehime Prefecture, Japan, mass mortalities of the pearl oyster Pinctada fucata have occurred since 1994. The occurrences of mass mortality roughly coincided with a shift of the dominant phytoplankton from Skeletonema and Chaetoceros to Chaetoceros and Nitzschia all of which belong to Bacillariophyceae. Hence, we evaluated Nitzschia, together with Chaetoceros and Isocrysis, as food for the oyster. Wet weights, lengths, widths, glycogen contents, and growth rates in terms of wet weight of the oysters in all the feeding treatments were significantly higher than those in the non-feeding treatment. The highest glycogen content (2.34%) and growth rate (2.21 g month⁻¹) were found in the Chaetoceros treatment. Growth rate in the Isocrysis treatment (1.63 g month⁻¹) was also high, although glycogen content in this treatment (0.41%) was low. In the Nitzschia treatment, growth rate of the oyster (0.94 g month⁻¹) was the lowest and glycogen content (0.83%) was also low relative to that in the Chaetoceros treatment. Chlorophyll a concentration in fecal pellets was lowest in the Nitzschia treatment (<2.7 μg mg⁻¹), suggesting more complete digestion of Nitzschia by the oyster. Thus, Nitzschia was edible and digestible but not assimilated by P. fucata. We propose the following scenario for the relationship between Nitzschia dominance and mass mortality. When Nitzschia dominates in a culture area, the physiological condition of P. fucata deteriorates due to low assimilation of Nitzschia by the oyster, followed by susceptibility of the oyster to infection by agents lethal to the oyster.     

Cloning, characterization and expression of cDNA containing major histocompatibility complex class I, IIα and IIβ genes of Japanese flounder Paralichthys olivaceus

ABSTRACT:   The nucleotide sequences of Japanese flounder Paralichthys olivaceus , major histocompatibility complex (MHC) cDNA, classical MHC class Iα, non-classical MHC class Iβ, MHC class IIα and IIβ, were determined. The domain structures and antigen binding motifs of vertebrate MHC are conserved in the Japanese flounder MHC. A phylogenetic analysis supports the classification of these genes into class I and class II MHC. Classical MHC class Iα was ubiquitously expressed, whereas the non-classical MHC class Iβ was expressed mainly in lymphoid organs, gills, intestine and stomach. The MHC classes IIα and IIβ were also ubiquitously expressed.     

Multiplication of attenuated and virulent porcine parvoviruses in colostrum-deprived, neonatal pigs

Colostrum-deprived, neonatal, 2 days old pigs were inoculated with the attenuated HT-/SK or the virulent 90HS strain of porcine parvovirus (PPV) by the oral or subcutaneous route and sacrificed 2, 4 or 6 days after inoculation. Then, comparison was made on viral multiplication in pigs between the two strains. Pigs inoculated with the HT-/SK strain showed no detectable viremia or HI antibody responses against PPV within 6 days after inoculation. Only in pigs inoculated by the subcutaneous route, a small amount of virus was recovered from the spleen, liver, or mesenteric lymph nodes. These viruses were distinguished from the parental virulent 90HS strain, as examined for rct maker in vitro. When pigs were inoculated with the virulent 90HS strain, viremia appeared in all of them 1 day after inoculation and continued for up to the sacrificed day. Moreover, a considerable amount of virus was also detected from all tissues, including brain, lung, liver, spleen, pancreas, small intestine, and lymph node tissues, in all pigs tested. HI antibodies were first detected 6 days after inoculation.     

Variation in life history parameters of the cardinalfish Apogonlineatus

ABSTRACT:   Life history parameters (growth pattern, the length of the spawningseason and age at sexual maturity) of Apogon lineatus wereinvestigated from three localities in Japan. The maximum ages werefound to be 3 years in Tokyo Bay, 2 years in Osaka Bay and 5 yearsoff Niigata Prefecture. Both sexes from Tokyo Bay grew to largersizes between the ages of 1 and 2 years than both sexes from otherlocalities, food availability being suggested as the major factorfor differences in growth. Spawning seasons were during 4 months(July–October) in Tokyo Bay and Osaka Bay, but were foundto only occur during the two months of July and August off NiigataPrefecture. Factors that could limit the spawning season off NiigataPrefecture were not determined. Age at maturity for both sexes inall localities appeared to be 1 year. We could not elucidate whetherthese variations in life history parameters arose from genetic differencesor from phenotypic plasticity. In either case, the trade-off betweenthe maximum age and the length of the spawning season in the offNiigata Prefecture population and any other population may be interpretedas an adaptation to local conditions, such as with the off NiigataPrefecture population.     

Paired box 7 inhibits differentiation in 3T3‐L1 preadipocytes

Myogenesis is precisely proceeded by myogenic regulatory factors. Myogenic stem cells are activated, proliferated and fused into a multinuclear myofiber. Pax7, paired box 7, one of the earliest markers during myogenesis. It has been reported that Pax7 regulates the muscle marker genes, Myf5 and MyoD toward differentiation. The possible roles of Pax7 in myogenic cells have been well researched. However, it has not yet been clarified if Pax7 itself is able to induce myogenic fate in nonmyogenic lineage cells. In this study, we performed experiments using stably expressed Pax7 in 3T3‐L1 preadipocytes to elucidate if Pax7 inhibits adipogenesis. We found that Pax7 represses adipogenic markers and prevents differentiation. These cells showed decreased expression of PDGFRα, PPARγ and Fabp4 and inhibited forming lipid droplets.