Effects of modern drainage systems on the spatial distribution of loach in rice ecosystems

• 1. Although rice fields support many aquatic species, recent agricultural intensification in Asia has led to loss of biodiversity, such as freshwater fish, in exchange for increased agricultural productivity. In Japan, modern drainage systems have been introduced in recent decades.
• 2. This study investigated the effects of several aspects of modern drainage systems on the spatial distribution of dojo loach Misgurnus anguillicaudatus, a dominant fish species in Japanese rice fields.
• 3. Multimodel inference approaches and hierarchical partitioning were used to estimate the direction and degree of the effect of each system on the spatial distribution of dojo loach.
• 4. Three variables related to modern drainage systems (gaps between fields and ditches, the type of drainage ditch, and the presence of underground drainage pipes), flooding dates, and spatial autocovariates showed significant influence on the abundance of loach. In particular, gaps had the largest impact among all the variables on loach in the later part of the survey (June).
• 5. Based on the results, the effectiveness of several conservation methods implemented for paddy‐dwelling fish in Japan was discussed. The knowledge will be a guide to the appropriate conservation of freshwater fish in Asia and other countries.

Copyright © 2011 John Wiley & Sons, Ltd.     

Prevalence of canine distemper virus, feline immunodeficiency virus and feline leukemia virus in captive African lions (Panthera leo) in Japan

Sero-prevalences of canine distemper virus (CDV), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) were evaluated in 20 captive lions in two Japanese zoos. Anti-CDV antibody was detected in 13 of 20 lions. We could pursue antibody responses against CDV in three lions back to 1996. Sera collected in 1996 were negative for anti-CDV antibody, therefore, all of them showed sero-conversion in 2000. This result suggested that the epidemic of CDV infection in this zoo might have happened between 1996 and 2000. The lions were also examined for FIV and FeLV infections. We had no evidence for FeLV infection but eight lions were sero-positive for anti-FIV antibody.     

Mechanisms responsible for reduced cardiotoxicity of mitoxantrone compared to doxorubicin examined in isolated guinea-pig heart preparations

We reported previously that doxorubicin, an anticancer agent that has an anthracycline structure, alters Ca2+ releasing and uptake mechanisms in the sarcoplasmic reticulum of myocardial cells. These effects of doxorubicin are apparently related to its cardiotoxicity. Mitoxantrone is a similar anticancer agent with an anthracenedion structure that has been shown to be significantly less cardiotoxic. In the present study, the effects of mitoxantrone on the functions of the sarcoplasmic reticulum were examined in isolated muscle preparations obtained from the guinea-pig heart. In electrically-stimulated left atrial muscle preparations, incubation in vitro for 4 hr with 30 or 100 microM mitoxantrone significantly prolonged the time to the peak of twitch tension, markedly increased the developed tension observed at lower stimulation frequencies, thereby attenuating the slope of positive force-frequency relationships, and increased the postrest contraction observed after a 60-sec quiescent period. In myocytes isolated from ventricular muscles, 30 microM mitoxantrone increased the peak and the size of intracellular Ca2+ concentrations ([Ca2+] i), and prolonged the time to peak [Ca2+]i. In skinned muscle fiber preparations obtained from the left ventricular muscle, 30 muM mitoxantrone significantly increased the caffeine-induced contraction without affecting the Ca2+ sensitivity of contractile proteins. These results suggest that mitoxantrone enhances Ca2+ release from the sarcoplasmic reticulum in isolated atrial muscle preparations obtained from the guinea-pig heart. Apparent enhancement of the sarcoplasmic reticulum functions, in contrast to anthracyclines that has been shown to suppress these functions, seems to explain the relative lack of marked cardiotoxicity of mitoxantrone.     

Comparison of the growth performances of offspring produced by a pair of cloned cattle and their nuclear donor animals

In the present study, the growth performance of a calf produced by mating a somatic cell cloned dam and sire was compared with that of its full siblings produced by mating the cattle used as nuclear donors for the cloned animals. The somatic cell cloned dam and sire were derived from cultured cumulus cells and ear cells, respectively. The cloned dam was artificially inseminated with semen from the cloned sire. A female calf was produced that was reared under general group feeding conditions. The calf was subjected to a clinical examination and to hematology, serum biochemistry, and telomere length analyses; all of these tests indicated that the calf was normal. The growth characteristics (body weight and shoulder height) of the calf fell within the range of the full siblings of the same sex produced by mating the animals used as the nuclear donors of clones. These findings suggest that the same breeding performance is expected from mating a cloned dam and sire as from mating the animals used as nuclear donors for the clones.     

Influence of swimbladder inflation failure on mortality,growth and lordotic deformity in Pacific bluefin tuna,Thunnus orientalis, (Temminck & Schlegel) postflexion larvae and juveniles

This study examined the influence of swimbladder inflation (SBI) failure on mortality (Experiment 1), lordotic deformity (Experiment 2) and growth (Experiment 1, 2) in Pacific bluefin tuna, Thunnus orientalis, postflexion larvae and juveniles by producing larvae lacking inflated swimbladders. Experiment 1 was conducted for postflexion larvae to juveniles (from 18 to 30 days‐post‐hatch; dph). Mortality was not significantly different between the fish with (WIS) and without (WOIS) inflated swimbladders. Standard length (SL) and body weight (BW) were significantly smaller in WOIS than WIS. Moreover, the SBI was found in WOIS after postflexion stage. In Experiment 2, two examination trials were conducted on SBI, vertebral deformity and growth for juvenile stage. Lordotic deformities were found neither in the WOIS nor in the WIS. Although SL and BW were significantly smaller in WOIS than WIS at 22 dph, after 37 dph no significant differences were found between them. The results of Experiment 1 and 2 indicate that SBI failure causes growth retardation until juveniles of 30 dph; however, it does not cause growth retardation in juveniles after 37 dph and mortality of postflexion larvae and juveniles. Moreover, SBI failure did not cause lordotic deformity in PBT differently from many other fish.     

Swimming angle and target strength of larval Japanese anchovy (<Emphasis Type="Italic">Engraulis japonicus</Emphasis>)

The swimming angle of larval Japanese anchovy (Engraulis japonicus) was measured in a tank, and target strength (TS) was calculated using a theoretical scattering model. The mean swimming angle was 12.8° (SD ±22.1). Increased speeds of flow led to increased mean swimming angles. The mean swimming angle at flow of 5 cm s⁻¹ was higher than at other speeds. TS values were estimated using a distorted-wave Born approximation model for two cases. Average values were 1–3 cm s⁻¹ (11.5° ± 22.1) and 5 cm s⁻¹ (16.6° ± 21.7) for cases 1 and 2, respectively. For case 1, TS ranged from −92.0 to −74.7 dB with a mean of −79.4 dB at 120 kHz. For case 2, TS ranged from −92.2 to −75.2 dB with a mean of −79.9 dB. The mean TS in case 2 was lower than that in case 1, with the maximum difference being 1.0 dB at 120 kHz (standard length 22.0 mm). However, there were no significant differences between the regression lines of cases 1 and 2. Thus, changes in flow speed altered the swimming angle of larval Japanese anchovy, but had little influence on TS.