The raccoon (Procyon lotor), indigenous to North America, has
naturalized in Japan as an invasive alien species, having been introduced into the country
in the 1970s. In Hokkaido, the northernmost island of Japan, feral raccoons have been
increasing in number and spreading throughout the island. The age at the onset of puberty
for raccoons is important for estimating individual lifetime reproductive success and
population growth. The present study investigated the timing of and potential factors
affecting the onset of puberty in male raccoons in Hokkaido. External characteristics and
histology of testes were studied in 151 male feral raccoons and in 1 captive juvenile. For
the majority of feral yearling raccoons, prepubertal development began in May, and
spermatozoa production began in October prior to their second mating season. However, some
larger juveniles attained puberty during the juvenile period. The captive juvenile, which
was fed throughout the winter, attained puberty only 11 months after birth. These results
suggest that if male raccoons can achieve enough body growth before the first mating
season, puberty can be attained early. In both juveniles and yearlings, spermatozoa
production was only observed after autumn. This timing coincided with the recrudescence of
seasonally active spermatogenesis in adult males. Therefore, attaining puberty in male
raccoons appears to require both adequate body nutrient development and several
environmental factors that control seasonal testicular changes. 相似文献
Fishery-independent surveys using sea surface trawl nets for Pacific saury Cololabis saira in the western North Pacific since 2003 have enabled the investigation of their annual distribution patterns and total biomass during June and July, prior to the main fishing season in Japan. We compared biomass estimates and their associated variances derived based on five different post-stratification approaches in a swept area method, and then observed that these approaches have little effect on biomass estimates and their precision, owing to well-organized survey designs and homogeneously allocated sampling stations. We were able to utilize decreasing biomass estimates for 15 years as an essential abundance index in the ongoing stock assessment. Notably, examination based on stratification along with longitudinal survey lines indicated that the estimated biomass had decreased in the western survey area, resulting in an eastward shift in the gravity center of Pacific saury distribution after 2010. We recommend biomass estimation in an east–west direction based on longitudinal stratification as an effective measure to develop population dynamics models which reflect westward migration into the fishing grounds around Japanese coastal waters, and to forecast the expected catch during the subsequent fishing period.
Bats are considered to be natural reservoirs for several viruses of clinical importance, including rabies virus, Nipah virus, and Hendra virus. Type I interferons (IFNs) is an important part of the immune system in the defense against viral infection. To investigate the function of type I IFNs upon viral infection in bats, the nucleic acid, and amino acid sequences of Egyptian Rousette (Rousettus aegyptiacus) IFN-alpha and -beta were characterized. Sequence data indicated that bat IFN-alpha consists of 562-bp encoded 187-aa, and IFN-beta consisted of 558-bp encoded 186-aa. Phylogenetic analysis of the overall identity of IFN-beta shared the highest sequence homology with pig IFN-beta in both nucleotide and amino acid level. Stimulation of bat primary kidney cells (BPKCs) and bat lung cell lines, Tb-1 Lu, with polyinosinic-polycytidylic acid (poly(I:C)) or exogenous bat type I IFNs resulted in increased type I IFNs mRNA expression in BPKCs, but not in Tb-1 Lu. Characterization of the bat IFN-alpha and -beta genes allows understanding of the immune responses upon stimulation in different tissues, thus providing practical strategies for control and treatment of clinically important diseases. These results are important especially for the virus infection, and suggest that future molecular studies on virus infection experiment of bats in vitro will require careful consideration of the differences of type I IFN expression patterns in different cell types. 相似文献
The raccoon is a seasonal breeder with a mating season in the winter. In a previous
study, adult male raccoons exhibited active spermatogenesis with high plasma testosterone
concentrations, in the winter mating season. Maintenance of spermatogenesis generally
requires high testosterone, which is produced by steroidogenic enzymes. However, even in
the summer non-mating season, some males produce spermatozoa actively despite low plasma
testosterone concentrations. To identify the factors that regulate testosterone production
and contribute to differences in spermatogenetic activity in the summer non-mating season,
morphological, histological and endocrinological changes in the testes of wild male
raccoons should be known. In this study, to assess changes in the biosynthesis, metabolism
and reactivity of testosterone, the localization and immunohistochemical staining
intensity of four steroidogenic enzymes (P450scc, P450c17, 3βHSD, P450arom) and the
androgen receptor (AR) were investigated using immunohistochemical methods. P450scc and
P450c17 were detected in testicular tissue throughout the year. Seasonal changes in
testosterone concentration were correlated with 3βHSD expression, suggesting that 3βHSD
may be important in regulating the seasonality of testosterone production in raccoon
testes. Immunostaining of P450arom and AR was detected in testicular tissues that
exhibited active spermatogenesis in the summer, while staining was scarce in
aspermatogenic testes. This suggests that spermatogenesis in the raccoon testis might be
maintained by some mechanism that regulates P450arom expression in synthesizing estradiol
and AR expression in controlling reactivity to testosterone. 相似文献
The equine herpesviruses are major infectious pathogens that threaten equine health. Equine herpesvirus 4 (EHV-4) is an important equine pathogen that causes respiratory tract disease, known as rhinopneumonitis, among horses worldwide. EHV-4 genome manipulation with subsequent understanding of the viral gene functions has always been difficult due to the limited number of susceptible cell lines and the absence of small-animal models of the infection. Efficient generation of mutants of EHV-4 would significantly contribute to the rapid and accurate characterization of the viral genes. This problem has been solved recently by the cloning of the genome of EHV-4 as a stable and infectious bacterial artificial chromosome (BAC) without any deletions of the viral genes. Very low copy BAC vectors are the mainstay of present genomic research because of the high stability of inserted clones and the possibility of mutating any gene target in a relatively short time. Manipulation of EHV-4 genome is now feasible using the power of BAC technology, and should aid greatly in assessing the role of viral genes in the virus-host interaction. 相似文献
To reveal whether bats serve as an amplifying host for Yokose virus (YOKV), we conducted a serological survey and experimentally infected fruit bats with YOKV isolated from microbats in Japan. YOKV belongs to the Entebbe bat virus group of vector unknown group within the genus Flavivirus and family Flaviviridae. To detect antibodies against YOKV, we developed an enzyme-linked immunosorbent assay (ELISA) using biotinylated anti-bat IgG rabbit sera. Serological surveillance was conducted with samples collected in the Philippines and the sera supplied from Malaysia. One of the 36 samples from the Philippines (2.7%) and 5 of the 26 samples from Malaysia (19%) had detectable ELISA antibodies. In the experimental infections, no clinical signs of disease were observed. Moreover, no significant viral genome amplification was detected. These findings revealed that YOKV replicates poorly in the fruit bat, suggesting that fruit bats do not seem to serve as an amplifying host for YOKV. 相似文献
Bumped kinase inhibitors (BKIs) target analog-sensitive kinases, which the genomes of mammals rarely encode. Previously, we demonstrated that a BKI effectively suppressed the in vitro replication of Toxoplasma gondii, the causative pathogen of toxoplasmosis, by targeting T. gondii calcium-dependent protein kinase 1 (TgCDPK1) (Eukaryotic Cell, 9: 667-670). Here, we examined whether the BKI 1NM-PP1 reduced parasite replication in vivo. A high dose of 1NM-PP1, by intraperitoneal injection, just before the parasite inoculation effectively reduced the parasite load in the brains, livers, and lungs of T. gondii-infected mice, however, a low dose of 1NM-PP1 with oral administration didn't change the survival rates of infected mice. 相似文献