Changes in neurosteroid biosynthesis during sexual maturation of lacustrine sockeye salmon

It was demonstrated that pregnenolone (P5) and 17α-hydroxypregnenolone (17α-OH-P5) were identified as cholesterol metabolites in the brain and pituitary gland of lacustrine sockeye salmon (Oncorhynchus nerka) during sexual maturation. Moreover, 17α-OH-P5 was determined as the major cholesterol metabolite. The conversion of P5 to 17α-OH-P5 in the brain and pituitary gland showed a clear regional difference, and their productivity were dramatically changed during sexual maturation. From these data, it was suggested that steroid converting enzyme in the brain and pituitary gland of lacustrine sockeye salmon might be involved in brain region-dependent roles on sexual maturation.     

The effect of brown kelp phenology on abalone locomotion and spatial distribution: acoustic telemetry and spatially explicit individual-based model approach

In field studies of a species’ population size, the movement and distribution of the target organism beyond the study area affect the population size estimate. Estimates are derived based on the number of animals caught, and catch efficiency changes with distribution and locomotion of the animals. This study, using acoustic telemetry and unmanned aerial vehicle (UAV) mapping, revealed that the Ezo abalone, Haliotis discus hannai, alters its distance moved depending on its distance from brown kelp. In addition, we reproduced abalone locomotion and brown kelp phenology as individual-based models. In the model, abalone moved to deeper water during the spring/summer brown kelp growing season, while during autumn/winter, the model showed them moving to shallower water and aggregating around the remaining brown kelp. The timing of moving to shallower area in the model coincided with the fishing season. Fishers mainly catch abalone in shallower areas. Therefore, it is possible that fishing efficiency will not decline later in the fishing season because fishers can catch the abalone immigrating to the main fishing grounds and those aggregating around the brown kelp. Our model indicated the need for improvement in the DeLury method and the catch per unit effort (CPUE) trends used in the abalone fishing industry.

     

Effect of climate and structure on the progression of wooden check dam decay

To gain better understanding of rates of decay of wooden check dams with different structures under different climate conditions, several dams of this type were examined under different environmental conditions over a 3 to 5-year period post-construction. Because a linear relationship was found between the mean (μ) and standard deviation (σ) of pilodyn penetration depth, mean penetration depth was taken as the indicator of deterioration, and relationships with check dam structural features and climate data recorded by AMEDAS were investigated. Multiple linear regression analysis revealed that temperature, climate index (CI) computed from rain days, warmth index computed from daily and annual mean air temperature, and altitude were the climate variables with the most effect on the rate of decay. With regard to dam structural features, factors such as specific discharge rate, water through width, dam length, and dam height had the most effect. Accordingly, in an effort to summarize the effects of climatic conditions and structural features, CI, altitude, and dam height were extracted as the most significant explanatory variables, and a formula for prediction of μ was obtained for each factor for up to 5 years post construction. The results showed that by taking into consideration regional conditions and calculating CI values from AMEDAS data, it is possible to predict the extent of decay of wooden check dams.     

Detection of RAPD markers linked to the everbearing gene in Japanese cultivated strawberry

To identify markers for the everbearing gene in strawberries, 199 F₁ progeny plants were produced from a cross between ‘Ever Berry’ (a Japanese everbearing strawberry) and ‘Toyonoka’ (a Japanese Junebearing strawberry) as the experimental population. The results of flowering tests produced 97 everbears and 102 Junebears. The chi‐square test gave a goodness of fit for the expected ratio of 1 : 1 for everbears to Junebears, suggesting the inheritance of the everbearing trait is controlled by a monogenic dominant gene. RAPD analyses on this trait were carried out using ‘Ever Berry’ and ‘Toyonoka’. Seventy‐one primers, which produced 89 polymorphic fragments between the two parents, were identified from a total of 175 primers. Five markers relating to the everbearing trait were selected from 26 of the 199 progeny plants. The remaining 173 seedlings were analysed with these five markers and a linkage map was constructed using all of the 199 F₁ progeny plants. The length of this linkage group is 39.7 cM. The closest markers found, OPE07‐1 and OPB05‐1, are respectively mapped at 11.8 and 15.8 cM on each side of the everbearing gene.     

Chromospheric anemone jets as evidence of ubiquitous reconnection

The heating of the solar chromosphere and corona is a long-standing puzzle in solar physics. Hinode observations show the ubiquitous presence of chromospheric anemone jets outside sunspots in active regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their velocity is 10 to 20 kilometers per second. These small jets have an inverted Y-shape, similar to the shape of x-ray anemone jets in the corona. These features imply that magnetic reconnection similar to that in the corona is occurring at a much smaller spatial scale throughout the chromosphere and suggest that the heating of the solar chromosphere and corona may be related to small-scale ubiquitous reconnection.     

Bovine C-terminal octapeptide of RFamide-related peptide-3 suppresses luteinizing hormone (LH) secretion from the pituitary as well as pulsatile LH secretion in bovines

Gonadotropin-inhibiting hormone (GnIH), observed in quail as a member of the RFamide neuropeptide family, suppresses luteinizing hormone (LH) secretion from the avian pituitary. Rats and cattle have an active gene of another member of the RFamide neuropeptide family, termed RFamide-related peptide-3 (RFRP-3), although bovine RFRP-3 is different from that of rats in both length and amino-acid sequence. A single injection of GnIH or RFRP-3 inhibited LH secretion in rodents, which continued for various periods. This study was conducted to evaluate the effects of bovine C-terminal octapeptide of RFRP-3 (RFRP-3-8) on LH secretion from cultured anterior pituitary (AP) cells of cattle, and the effects of RFRP-3-8 injections on pulsatile LH secretion in castrated male calves. The suppressive effect of RFRP-3-8 on LH secretion from AP cells was observed in the presence of gonadotropin-releasing hormone (GnRH), but not in the absence of GnRH in culture media. In another experiment collecting blood samples serially from castrated male calves with repeated intravenous injections of RFRP-3-8 (n = 6) or saline (n = 6), the RFRP-3-8 group showed suppressed LH pulse frequency during the injection period (P < 0.05); however, the RFRP-3-8 group showed no difference from the saline group in all measures of LH secretion in the postinjection period. In conclusion, our results suggested that RFRP-3-8 suppresses LH secretion from cultured AP cells, as well as LH pulse frequency in cattle.     

Immune defence mechanism against blood-borne Pasteurella multocida in turkeys

Humoral and cellular immune defence factors involved in controlling blood-borne Pasteurella multocida were investigated in turkeys by the passive transfer of immune serum or by the treatment with macrophage-activating agents. The treated and untreated birds were intravenously inoculated with a virulent strain of P multocida, and the viable bacteria in the blood, liver and spleen were counted. In untreated birds, the bacteria were rapidly removed from the blood, and the majority were recovered from the liver and spleen 120 minutes after inoculation. Neither the transfer of immune serum nor the treatment with macrophage-activating agents significantly influenced the clearance rate of bacteria from the blood. The number of bacteria recovered from the liver 120 minutes after inoculation was slightly lower in the birds treated with macrophage-activating agents and significantly lower in those given immune serum than in the untreated birds. None of the treatments, however, significantly changed the number of bacteria recovered from the spleen 120 minutes after inoculation. The results suggest that the phagocytes in the liver, but not in the spleen, play a crucial role in the intravascular defence against P multocida in the presence of specific antibodies.