Cloning of kuruma prawn Marsupenaeus japonicus crustin-like peptide cDNA and analysis of its expression

ABSTRACT:   Antimicrobial peptides serve as an important component of the innate immune system of all species by functioning to provide a rapid first line defense against infection. Arthropod antimicrobial peptides have been well described in insects, whereas only a few molecules have been identified in crustaceans. Five variants (types 1–5) of Marsupenaeus japonicus crustin-like peptide cDNA that were obtained from a hemocyte cDNA library and polymerase chain reaction (PCR) amplification are reported here. Marsupenaeus japonicus crustin-like peptide type 1, the predominant type, has a cDNA consisting of 679 nucleotides and an open reading frame consisting of 573 base pairs coding for 191 amino acid residues. Other types contain varying glycine-rich repeats at the N-terminal amino acid sequences. The deduced amino acid sequences of these variants are highly similar to those of Litopenaeus setiferus (80% identity), Litopenaeus vannamei (80% identity) and Carcinus maenas crustins (44% identity). Expression of Marsupenaeus japonicus crustin-like peptide mRNA was detected in hemocytes, but not in the heart, hepatopancreas, gill, fore-gut, mid-gut, muscle, subcuticular epithelium or ovary. The expression level of crustin-like peptide mRNA increased significantly 1, 3 and 7 days post-peptidoglycan feeding as determined by quantitative real-time PCR. These results suggest that crustin-like peptide could have an important role in shrimp defense mechanisms.     

Changes in plasma somatolactin levels during spawning migration of chum salmon (Oncorhynchus keta)

Plasma somatolactin (SL) concentrations were examined in chum salmon in relation to gonadal maturation; immature salmon in the Bering Sea at various stages of maturation, and mature salmon during upstream migration caught at the ocean, bay and river. Plasma SL concentrations as well as plasma prolactin (PRL) and growth hormone (GH) levels in the immature fish caught in the Bering Sea were maintained essentially at similar levels. Plasma SL in mature salmon increased significantly from the fish in the ocean to the fish in the river in both sexes. Although all the fish had fully developed gonads, females completed ovulation while still in the bay, whereas final spermeation in males was achieved after entry into the river. Thus, no clear correlation was seen between plasma SL levels and final gonadal maturation. On the other hand, plasma PRL concentrations in both male and female fish were higher in the fish in the river than those in the ocean and bay, and plasma GH levels were higher in both sexes in the fish in the bay and river than those in the ocean. Plasma levels of triglycerides, glucose, free fatty acids and ionized sodium and calcium were also examined. Significant-negative correlations were seen between plasma SL and plasma ionized calcium in mature male salmon, and between plasma SL and plasma triglycerides in mature female salmon. Although our findings do not rule out the possibility of the involvement of SL in final maturation, the results indicate that SL seems to be involved at least in energy and/or calcium metabolism during the spawning migration.     

Distribution of the Steller sea lion Eumetopias jubatus during winter in the northern Sea of Japan, along the west coast of Hokkaido, based on aerial and land sighting surveys

Aerial and land-based sighting surveys were conducted to clarify the distribution of Steller sea lions during winter in the northern Sea of Japan, along the west coast of Hokkaido, from 2001 to 2003. Aerial surveys revealed that sea lions gathered around the Rishiri-Rebun Islands in March 2002 and 2003, and between Iwanai and Cape Obana in February 2003. Higher numbers of sea lions were also confirmed at Cape Ofuyu and Cape Kamui on the central-west coast compared to that at the haul-out sites in the 1980s on the upper-west coast in March 2002 and 2003. Additionally, fisherman observed sea lions along the coast of the Tsugaru Strait from February to May 2003, where the presence of sea lions was not reported in the 1980s. These facts suggest that sea lions have recently expanded their distribution southward. Land-based surveys at the recent haul-out sites indicated that sea lions in the central-west coast were composed mainly of adult and subadult males (average: Cape Ofuyu 75.2%, Cape Kamui 69.5%), which stayed from November 2002 to May 2003. In this area, sea lions arrived earlier and stayed longer than in the 1980s.     

Effect of food amount and temperature on growth rate and aerobic scope of juvenile chum salmon

Offshore migration of Pacific salmon Oncorhynchus spp. is partly triggered by increasing body size and high motility in the early stages of life. The survival of juvenile salmon may depend on their growth rate during the first few months in the sea, and this factor partly regulates the dynamics of adult populations. Here, we assessed the effects of water temperature and food availability on the growth of juvenile chum salmon O. keta. In addition, by combining the measurements of metabolic performance for growth and activity (Absolute Aerobic Scope: AAS) with a bioenergetics model, we estimated the energy allocation for different activities in the juveniles. Under high temperatures (14 °C), juveniles reared at low food levels (1% body weight) allocated less than half their energy for growth than those reared at high food levels (4% body weight). These findings suggest that high temperature and low food level constrain the growth of juveniles, providing an insight into the effect of the recent increase in warm and low-nutrient water masses on survival of juveniles and catches of adult chum salmon on the Pacific side of Honshu Island, Japan.

     

Concentrations of ketone body and antidiuretic hormone in cerebrospinal fluid in response to the intra‐ruminal administration of butyrate in suckling calves

The aim of the present study was to elucidate the mechanism by which ketone bodies increase antidiuretic hormone (ADH) secretion. Four male Holstein calves (5 weeks of age) were utilized. Four levels of butyrate (0 g, 11 g, 22 g and 44 g) were administrated intra‐ruminally in a 4 × 4 Latin square design and cerebrospinal fluid (CSF, six‐position lumbar puncture), blood plasma and urine were collected. The concentration of total plasma and CSF protein was 5.5–5.6 g/dL and 27.5–28.3 mg/dL, respectively. CSF concentrations of a specific ketone body, 3‐hydroxybutyric acid, were significantly higher in the 22 g and 44 g butyrate groups than in the control group. CSF concentrations of ADH in the 11 g and 44 g butyrate groups were significantly higher than in the control group. Plasma concentration of 3‐hydroxybutyric acid was increased by intraruminal administration of butyrate within 15 min in a dose‐dependent manner, and it was higher in the 22 g and 44 g butyrate group than in the control group from 15 min to 4 h. With the exception of the 11 g butyrate group, plasma concentrations of ADH also increased in response to butyrate treatment, and it was higher in the 44 g butyrate group than in the 22 g butyrate group from 15 min to 1.5 h. The duration of the elevated plasma concentrations of ADH was shorter than that of the plasma concentration of 3‐hydroxybutyric acid. The relationship between the plasma concentrations of ADH and 3‐hydroxybutyric acid was statistically significant but the correlation between the two concentrations was not high. Butyrate treatment elevated the plasma concentration of ADH and also resulted in reduced urine volume and increased urine osmolality. Haematocrit (Ht) values, and the osmolality of CSF and plasma were not different among the groups. Our results suggested that the increased ADH secretion observed in suckling calves fed dry feeds was caused by butyrate‐derived ketone body that crossed the blood‐brain barrier rapidly.     

Optimization of the supplemental essential amino acids to a fish meal-free diet based on fermented soybean meal for rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>

To minimize the supplemental essential amino acids (EAAs) to a fish meal-free diet for rainbow trout Oncorhynchus mykiss, four types of fish meal-free diets and a control fish meal-based diet were fed to triplicate groups of trout (initial BW, 16 g) for 10 weeks. Two fish meal-free diets based on a fermented and an unfermented soybean meal were unsupplemented with EAAs (diet FSBM and SBM), and two fish meal-free diets based on the fermented soybean meal were supplemented with a combination of lysine and methionine (diet F + ML) and all EAAs (diet F + All), the EAA contents of which were lower than those of the control diet (diet FM). Although physiological conditions such as the biliary bile acid status and morphological features of fish fed diet FSBM were improved and similar to those of fish fed diet FM, the growth performance was not significantly different (P > 0.05) from fish fed diet SBM. The growth performances and whole body protein contents of fish fed F + ML and F + All diets were similarly improved compared to fish fed diet FSBM. These findings indicate that supplementation of lysine and methionine to a fermented soybean meal-based fish meal-free diet is enough to maximize the amino acid utilization of the diet.     

Prognosis of canine patients with nasal tumors according to modified clinical stages based on computed tomography: a retrospective study

To evaluate the efficacy of clinical staging based on computed tomography (CT) imaging over the World Health Organization (WHO) staging system based on radiography for nasal tumors in dogs, a retrospective study was conducted. This study used 112 dogs that had nasal tumors; they had undergone radiography and CT and had been histologically confirmed as having nasal tumors. Among 112 dogs, 85 (75.9%) were diagnosed as adenocarcinoma. Then they were analyzed for survival time according to each staging system. More than 70% of the patients with adenocarcinoma were classified as having WHO stage III. The patients classified under WHO stage II tended to survive longer than those classified under WHO stage III. Dogs classified under WHO stage III were further grouped into CT stages III and IV, and CT stage III patients had a significantly longer survival time than CT stage IV patients. In addition, patients treated with a combination of surgery and radiation had a significantly longer survival time than the patients who did not receive any treatment in CT stage III. On the other hand, different treatment modalities did not show a significant difference in the survival time of CT stage IV dogs. The results suggest that WHO stage III dogs may have various levels of tumor progression, indicating that the CT staging system may be more accurate than the WHO staging system.