Thioacetamide-induced Hepatocellular Necrosis Is Attenuated in Diet-induced Obese Mice

To assess modification of thioacetamide-induced hepatotoxicity in mice fed a high-fat diet, male C57BL/6J mice were fed a normal rodent diet or a high-fat diet for 8 weeks and then treated once intraperitoneally with thioacetamide at 50 mg/kg body weight. At 24 and 48 hours after administration, massive centrilobular hepatocellular necrosis was observed in mice fed the normal rodent diet, while the necrosis was less severe in mice fed the high-fat diet. In contrast, severe swelling of hepatocytes was observed in mice fed the high-fat diet. In addition, mice fed the high-fat diet displayed more than a 4-fold higher number of BrdU-positive hepatocytes compared with mice fed the normal rodent diet at 48 hours after thioacetamide treatment. To clarify the mechanisms by which the hepatic necrosis was attenuated, we investigated exposure to thioacetamide and one of its metabolites, the expression of CYP2E1, which converts thioacetamide to reactive metabolites, and the content of glutathione S-transferases in the liver. However, the reduced hepatocellular necrosis noted in mice fed the high-fat diet could not be explained by the differences in exposure to thioacetamide or thioacetamide sulfoxide or by differences in the expression of drug-metabolizing enzymes. On the other hand, at 8 hours after thioacetamide administration, hepatic total glutathione in mice fed the high-fat diet was significantly lower than that in mice fed the normal diet. Hence, decreased hepatic glutathione amount is a candidate for the mechanism of the attenuated necrosis. In conclusion, this study revealed that thioacetamide-induced hepatic necrosis was attenuated in mice fed the high-fat diet.     

ATP depletion inhibits retraction of chromatophores induced by GABA in cephalopod Todarodes pacificus

Color changes in cephalopods are generated by the expansion or retraction of chromatophores located under the dermis. The behavior of the chromatophores is regulated by neurotransmitters; l-glutamate (l-Glu) is an excitatory transmitter that causes the chromatophores to expand. To date, serotonin [5-hydroxytryptamine (5-HT)] is the only neurotransmitter known to stimulate retraction of chromatophores. We found that the chromatophores in the Japanese squid Todarodes pacificus were regulated by γ-aminobutyric acid (GABA), an inhibitory neurotransmitter, and that GABA caused expanded chromatophores to retract. We also found that adenosine 5′-triphosphate (ATP) concentrations in skin samples remained stable at their initial values for more than 24 h after the death of each squid; therefore, the chromatophores could respond to both l-Glu and GABA during that period. Furthermore, we attempted to reduce the levels of ATP by storing skin sample in sodium azide solution. The chromatophores in sodium azide-treated skin samples were induced to expand by l-Glu, but these expanded chromatophores could not be induced to retract by GABA. Based on these observations, we conclude that ATP is essential for retraction, but not expansion, of chromatophores.     

Bioremediation of organically enriched sediment deposited below fish farms with artificially mass-cultured colonies of a deposit-feeding polychaete <Emphasis Type="Italic">Capitella</Emphasis> sp. I

ABSTRACT:   For bioremediation of organically enriched sediment deposited below fish farms, the extremely high potential for population growth of a deposit-feeding polychaete, Capitella sp. I, in the organically enriched sediment, and the effect on decomposition of organic matter in the sediment, were examined. A mass-culturing technique was conducted for this species. Bioremediation experiments were conducted on the organically enriched sediment in a fish farm in Kusuura Bay, Japan in 2003–2006. Approximately 1.7 million individuals of the worms were placed on the sediment below one net pen in December 2003, 9.3 million individuals in November 2004, and 2.2 million individuals in November 2005. After the worms were spread on the sediment, they rapidly increased in number and reached the highest densities of approximately 134 000 inds/m² in February 2004, 527 000 inds/m² in March 2005 and 103 000 inds/m² in January 2006. In the process of rapid population growth, the decomposition of the organic matter of the sediment was enhanced markedly. Our results demonstrate that the promotion of population growth by spreading cultured colonies of Capitella can enhance the decomposition rate of organic matter markedly in organically enriched sediment below fish farms. This method is promising for minimization of the negative effects of fish farms.     

Genotyping of Giardia intestinalis from domestic and wild animals in Japan using glutamete dehydrogenase gene sequencing

To determine the genotypes of Giardia intestinalis from domestic and wild animals in Japan, Giardia isolates obtained from feces of 24 dogs kept in households and breeding kennels, three companion cats, five dairy calves and three wild monkeys, Macaca fuscata, were genotyped using the 177 bp sequence of the glutamete dehydrogenase gene (gdh). The genotypes were assemblages A, C, D or A/D for dog isolates, Assemblage F for cat isolates, assemblages A or E for calf isolates and assemblage B for monkey isolates. This is the first report on the genotypes of Giardia isolates from cats, calves and wild monkeys in Japan.     

In vitro techniques for genomic alteration in rice plants

Because of the explosive increase in world population, a sufficient food supply must be achieved by varietal improvement in the major cereal crops including rice. It is expected that new in vitro techniques incombination with conventional breeding methods may effectively raise the yield potential. On the other hand, there are many environmental problems to be solved world-wide such as, global warming, environmental pollution, ecological destruction, reduction in water supplies and so on. Therefore, it is necessary to rapidly develop new varieties for the future combining of higher yield potential with excellent grain quality, and resistance to both biotic and abiotic stresses for the promotion of sustainable agriculture. Although many efforts have been made to introduce useful traits from wild species to cultivated rice via hybridization, it is still difficult to overcome breeding barriers such as cross incompatibility and hybrid sterility and inviability in practical breeding. Now in vitro techniques are going to make it possible to use genetic manipulation and cell culture and fusion techniques to speed up the breeding process. For sustainable agriculture, it is important to utilize the useful genes from alien species. For this purpose, asymmetric protoplast fusions have already been used successfully to transfer disease resistance in Brassica napus. In this experiment, a high level of resistance to the rice blast disease was transferred from wild species through asymmetric fusions. It is also noted that manipulation of cytoplasmic genomes is possible through asymmetric fusions as shown in the induction of new cytoplasmic male sterility (CMS). This revised version was published online in August 2006 with corrections to the Cover Date.     

Pneumocystis Pneumonia in a Thoroughbred Racehorse

Pneumocystis pneumonia is an opportunistic respiratory infection that occurs in immunocompromised animals. In horses, pneumocystic pneumonia is observed mostly in foals and often progresses rapidly. Here, we report pneumocystic pneumonia in a Thoroughbred racehorse. A 3-year-old Thoroughbred racehorse colt had marked respiratory symptoms for 3 weeks and was unresponsive to antibiotic treatment. At necropsy, firm, tan, patchy lesions were scattered diffusely in the lungs. Microscopically, alveolar septa thickened by proliferation of collagen fibers and infiltration of inflammatory cells were observed. In the alveolar spaces, many brown-black yeast-like organisms similar to cystic forms of Pneumocystis carinii were recognized by staining with Gomori's methenamine silver. Bronchoalveolar lavage fluid (BALF) obtained before necropsy included macrophages engulfing the fungus bodies. Amplified products were obtained from BALF and lung tissue samples by Pneumocystis-specific nested PCR. Phylogenetic analysis based on the 18S rRNA gene sequence revealed that the P. carinii organism from BALF was related to the Pneumocystis spp. detected in other animals and was especially close to P. carinii derived from ferrets. This is a rare case of pneumocystic pneumonia in a colt with chronic pulmonary lesions.     

Immune control of Babesia bovis infection

Babesia bovis causes an acute and often fatal infection in adult cattle, which if resolved, leads to a state of persistent infection in otherwise clinically healthy cattle. Persistently infected cattle are generally resistant to reinfection with related parasite strains, and this resistance in the face of infection is termed concomitant immunity. Young animals are generally more resistant than adults to B. bovis infection, which is dependent on the spleen. Despite the discovery of B. bovis over a century ago, there are still no safe and effective vaccines that protect cattle against this most virulent of babesial pathogens. Immunodominant antigens identified by serological reactivity and dominant T-cell antigens have failed to protect cattle against challenge. This review describes the innate and acquired immune mechanisms that define resistance in young calves and correlate with the development of concomitant immunity in older cattle following recovery from clinical disease. The first sections will discuss the innate immune responses by peripheral blood- and spleen-derived macrophages in cattle induced by B. bovis merozoites and their products that limit parasite replication, and comparison of natural killer cell responses in the spleens of young (resistant) and adult (susceptible) cattle. Later sections will describe a proteomic approach to discover novel antigens, especially those recognized by immune CD4+ T lymphocytes. Because immunodominant antigens have failed to stimulate protective immunity, identification of subdominant antigens may prove to be important for effective vaccines. Identification of CD4+ T-cell immunogenic proteins and their epitopes, together with the MHC class II restricting elements, now makes possible the development of MHC class II tetramers and application of this technology to both quantify antigen-specific lymphocytes during infection and discover novel antigenic epitopes. Finally, with the imminent completion of the B. bovis genome-sequencing project, strategies using combined genomic and proteomic approaches to identify novel vaccine candidates will be reviewed. The availability of an annotated B. bovis genome will, for the first time, enable identification of non-immunodominant proteins that may stimulate protective immunity.