In vivo and in vitro effects of Rhizopus extract on body growth and steroid production in masu salmon, Oncorhynchus masou Brevoort

This study investigated the in vivo and in vitro effects of Rhizopus (filamentous fungus) extract (RU) in masu salmon Oncorhynchus masou Brevoort. Underyearling fish were fed with RU for 16 months. Monthly changes in body growth, gonadal maturation and serum levels of sex steroids were monitored. Gonads were also incubated at 0, 1, 10, 100 and 1000 μg RU mL⁻¹ Leibovitz's L‐15 medium for 18 h. The levels of steroids in serum and cultured medium were measured. It was determined that RU‐fed immature and mature males, when compared with control groups, showed significantly higher body growth during spring, summer and the spawning period. Similarly, immature RU‐fed females showed significantly higher fork length and body weight in autumn, spring and summer. Furthermore, RU‐fed males showed significantly higher levels of serum testosterone (T) and 11‐ketotestosterone (11‐KT) levels in the pre‐spawning season, and 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) in the spawning season. In vitro RU incubation of gonads showed a dose‐dependent and significant increase in T, 11‐KT, oestradiol‐17β and DHP release in the medium. It appears that the causes of enhanced body growth and increased steroid production herein observed in salmonids are the physiologically active substances that may be present in the mycelium of the fungus.     

EMG telemetry studies on upstream migration of chum salmon in the Toyohira river,Hokkaido, Japan

The movements of 28 adult chum salmon, Oncorhynchus keta (Walbaum) tagged with electromyogram (EMG) transmitters were tracked along the Toyohira river, Hokkaido, Japan, in October of 2007 and 2008 to investigate and evaluate the upstream migratory behavior through the protection bed and fishway of ground sills. The approach time of fish that ascended successfully through the protection bed and fishway was shorter than that of unsuccessful fish. The unsuccessful fish were observed to swim in currents with high water velocity and shallow water depth at swimming speeds that exceeded their critical swimming speed (U _crit) during the approach to these structures. In consequence, unsuccessful fish frequently alternated between burst and maximum sustained speeds without ever ascending the fishway, and eventually became exhausted. It is important that fishway are constructed to enable chum salmon to find a passage way easily, so that they can migrate upstream rapidly without wasting excessive energy.     

Dominant effects of litter substrate quality on the difference between leaf and root decomposition process above- and belowground

Initial decomposition rates, changes in organic chemical components (acid-insoluble fraction, holocellulose, polyphenols, soluble carbohydrates) and nutrient dynamics (K, Mg, Ca, P, N) were examined for fine roots and leaves of Japanese cypress (Chamaecyparis obtusa). Litterbag experiments designed to evaluate the relative effects of litter type and position of litter supply in the soil were carried out, considering that root and leaf litter typically occupy different locations and have different substrate qualities. Litterbags of roots and leaves were placed at two positions (on the soil surface and in the humus layer), and collected every 3 months over one year. The mass loss rate and N release were slower during root decomposition in the humus layer than during leaf decomposition on the soil surface. These differences between root and leaf decomposition were mainly caused by the litter type, and the effect of the position on decomposition was relatively small. Root litter was less influenced by position related effects, such as differences in humidity, than leaf litter, and this recalcitrant trait to environmental effects may be responsible for the slower mass loss rate and N release in root decomposition. The results of the present study suggest that fine roots are persistent in the soil and serve an important role in N retention in forest ecosystems because of their litter substrate quality.     

Application of the Tweedie distribution to zero-catch data in CPUE analysis

We focus on the zero-catch problem of CPUE (catch per unit effort) standardization. Because the traditional CPUE model with a log-normal error structure cannot be applied in this case, three methods have often been utilized as follows:

(1) Ad hoc method adds a small constant value to all response variables.

(2) Catch model with a Poisson or negative-binomial (NB) error structure.

(3) Delta-type two-step method such as the delta-normal model (after estimating the ratio of zero-catch using a logit or probit model, a model such as CPUE log-normal or Catch-Poisson is applied to CPUE without zero-data).

However, there are some statistical problems with each of these methods.In this paper, we carried out the CPUE standardization mainly using the Tweedie distribution model based on the actual by-catch data (silky shark, Carcharhimus falciformis, in the North Pacific Ocean caught by Japanese training vessels) including many observations with zero-catch (>2/3rd) and tuna fishery data as a target (yellowfin tuna, Thunnus albacares, in the Indian Ocean caught by Japanese commercial vessels) where the ratio of zero-catch is not so high (<1/3rd). The Tweedie model is an extension of compound Poisson model derived from the stochastic process where the weight of the counted objects (i.e., number of fish) has a gamma distribution and has an advantage of handling the zero-catch data in a unified way.We also compared four candidate models, the Catch-NB model, ad hoc method, Delta-lognormal model (delta-type two-step method) and Tweedie distribution, through CPUE analyses of actual fishery data in terms of the statistical performance. Square error and Pearson's correlation coefficient were calculated based on the observed CPUE and the corresponding predicted CPUE using the n-fold cross-validation.As a result, the differences in the trend of CPUE between years and model performance between the ad hoc method and Tweedie model were found to be not so large in the example of yellowfin tuna (target species). However, the statistical performance of Tweedie distribution is rather better than Delta-lognormal model, the Catch-NB distribution and ad hoc method in the example of silky shark (by-catch species). Standardized CPUE year trend of ad hoc method was found to be quite different from that of the Tweedie distribution and other two models. Model performance of the Tweedie distribution is good judging from the 5-fold cross-validation using the fishery data if including many zero-catch data such as by-catch species.     

Ability of salmon growth hormone to accelerate somatic growth of juvenil abalone Haliotis discus hannai

ABSTRACT:   The ability of salmon growth hormone (sGH) to accelerate the somatic growth of juvenile abalone Haliotis discus hannai by immersion was examined. After immersion for one hour into a sGH-rich solution at a concentration of 30 mg/L, the sGH immunoreactivity in the body fluid of abalone was maximal after one day, and levels were still detectable at two days. No immunoreactivity was observed in the control group. Following immersion for one hour at one or two-week intervals for 120 weeks into the sGH-rich solution at 30 mg/L, the sGH-immersed abalone exhibited a significant increase in shell length and body weight. On the other hand, abalone immersed into a salmon prolactin (sPRL)-rich solution at 30 mg/L for one hour showed a lower increase in both shell length and body weight than the sGH-immersed abalone. No increases in shell length and body weight were observed in either the bovine serum albumin-immersed abalone or untreated controls. These results provide evidence that sGH can be transported from ambient water into the circulatory system of abalone, and can subsequently improve the somatic growth of juveniles.     

Interactions between different genotypic tissues in citrus graft chimeras

The heritability of tolerance of wheat F₃ lines to competition from annual ryegrass (Lolium rigidum), and its relationship to morphological traits, were determined using crosses between wheat cultivars with good and poor competitive ability. Forty F₂-derived F₃ lines from a cross between two late flowering varieties (Machete × Spear) and 40 from a cross between early flowering varieties (Wilgoyne × Gutha) were grown in the field with and without annual ryegrass. There was significant genetic variation between lines within each of the two populations in a number of aspects of plant growth and development, including yield in monoculture. The estimates of heritability for % yield loss due to competition were 0.25 and 0.57 in the two crosses respectively, indicating that selection for high tolerance to competition in the F₃ generation or later should be effective. Fairly strong relationships between height and % yield loss and between leaf length and % yield loss suggest that these may be useful auxiliary traits when selecting for low % yield loss. However, differences between crosses in the magnitude and sign of genetic and phenotypic correlation between traits indicate that competitive ability is a complex character influenced by many factors. This revised version was published online in August 2006 with corrections to the Cover Date.     

Amphidiploids between Cyclamen persicum Mill. and C. purpurascens Mill. induced by treating ovules with colchicine in vitro and sesquidiploids between the amphidiploid and the parental species induced by conventional crosses

Summary We cultured colchicine-treated hybrid ovules in vitro to produce fertile amphidiploids of C. persicum (2n=2x=48. referred to as AA) × C. purpurascens (2n=2x=34, referred to as BB). Seedlings and mature plants were obtained from the ovules without colchicine and those exposed to 50 mg/l colchicine for 5, 10 and 15 days, whereas they were not obtained from the ovules exposed to 50 mg/l colchicine for 20 days and 500 mg/l for 5, 10, 15 and 20 days. Although 8 mature hybrids derived from the ovules without colchicine produced a few fertile pollen grains, they failed to produce viable seeds by self-fertilization. The hybrids had 41 somatic chromosomes. Four and 3 mature plants were derived from ovules exposed to 50 mg/l colchicine for 10 and 15 days, respectively. One each among 4 and 3 mature plants showed a high frequency of pollen grain fertility, produced several seeds by self-fertilization, and had 82 somatic chromosomes which is twice the number of hybrid chromosomes (2n=41, AB). These findings indicated that these plants are amphidiploids (2n=82, AABB) between C. persicum and C. purpurascens. Three and 2 viable seeds were derived by the conventional crosses of diploid C. persicum × the amphidiploid and the amphidiploid × C. purpurascens, respectively. Flowering plants that developed from the seeds of diploid C. persicum × the amphidiploid were barely fertile and had 65 somatic chromosomes (2n=65, AAB), whereas those that developed from the seeds of the amphidiploid × C. purpurascens were barely fertile and had 58 somatic chromosomes (2n=58, ABB). The somatic chromosomes indicated that these plants are probably sesquidiploids between the amphidiploid and either C. persicum or C. purpurascens. The interspecific cross-breeding of cyclamen using the amphidiploids and the sesquidiploids is discussed.     

Effects of heating on the interaction of lipid and zein in a dry powder system

The effects of heat treatment on the interaction of lipid and zein in a dry powder system were investigated. Linolenic acid ethyl ester (LAE) was mixed with the zein powder. The glass transition temperature (T(g)) for the dry powder zein was shown to be approximately 107 degrees C by differential scanning calorimetry. The thermogram of the zein-LAE mixed powder showed an exothermic transition near the T(g) of zein. Fourier transform infrared (FT-IR) spectroscopy was used for detecting the structural changes in zein by heat treatment, that is, elevating the temperature from 25 to 160 degrees C. The heat treatment of the powdery zein with and without LAE caused increases in the alpha-helix, beta-turn, and beta-sheet, concomitant with decreases in the intermolecular hydrogen-bonded beta-sheet and random coil. Such changes in the secondary structure were more drastic for the powder with LAE. The heating of the zein-LAE mixed powder also caused decreases in the peaks originating from LAE in the FT-IR spectra. These results suggest that the heat treatment induced the interaction of the zein and LAE in the powdery system. The influence of heating on the antioxidative activity of dry powder zein was studied by measurements of the peroxide value. When zein-LAE mixed powder was heated before storage, the oxidation of LAE was inhibited for 7 days, whereas LAE was oxidized within 1 day in the absence of heat treatment.