Validation of the sperm quality analyzer and the hypo-osmotic swelling test for frozen-thawed ram and minke whale (Balaenoptera bonarensis) spermatozoa

The object of the present study was to investigate the validation of the sperm quality analyzer (SQA) and the hypo-osmotic swelling (HOS) test with standard sperm analysis methods in frozen-thawed ram and minke whale spermatozoa. In rams, highly significant correlations were observed in the percentage of motile spermatozoa (P<0.01) and sperm concentration (P<0.01) between the standard and SQA methods. But, the percentage of morphologically normal spermatozoa did not significantly correlate between the standard and SQA methods. The percentages of swollen spermatozoa at 15 minutes by the HOS test were significantly correlated with the motility by the standard (P<0.05) and by the SQA (P<0.05) methods. For minke whale spermatozoa, the SVI (sperm viability index) values by the standard method were significantly (P<0.001) correlated with the sperm motility index (SMI) values by SQA. The percentage of motile spermatozoa was also significantly correlated (P<0.01) with the motility measured by SQA. Using different hypo-osmotic solutions and incubation times, the HOS test with 25, 100 and 150 mOsM did not show significant variations. Motility observed by the standard method and the percentage of swollen spermatozoa were significantly correlated (P<0.05). These results indicate that the SQA and HOS test can be utilized to assess the post-thawing motility of ram and minke whale spermatozoa, and that the SQA and HOS test values are significantly correlated in ram spermatozoa. However, sperm concentration and morphologically normal spermatozoa are not assessed accurately by SQA in minke whales.     

Follicular development after ovum pick-up and fertilizability of retrieved oocytes in postpartum dairy cattle

This study aimed to evaluate gonadotropin secretion and the developmental competence of follicular oocytes in dairy cattle during the early postpartum (PP) period. The number of follicles developed after transvaginal ultrasound-guided ovum pick-up (OPU) and fertilizability of retrieved oocytes were compared between cows in which the first dominant follicle (DF) ovulated (ovulated group, n=4) and did not ovulate (non-ovulated group, n=3), and between early PP (early PP group, n=2) and after the resumption of the estrous cycle (cyclic group, n=2). Follicular ablation was performed 2-4 days after the detection of DF in the second follicular wave PP. OPU was repeated 3-5 times at 3 or 4-day intervals from 3-4 days after the follicular ablation. At OPU, the follicles were enumerated and all those > or = 5 mm in diameter were aspirated. Recovered oocytes were subjected to in vitro maturation and fertilization. Both criteria were similar between ovulated and non-ovulated groups, and between early PP and cyclic groups. These results suggest that FSH/LH secretions required for follicle recruitment and subsequent follicular growth during the early PP period are similar to those after resumption of the estrous cycle. They also indicate that follicular oocytes during the early PP period have developmental competence.     

Spatial distribution analysis of the North Pacific spiny dogfish,Squalus suckleyi,in the North Pacific using generalized additive models

The North Pacific spiny dogfish (SPD), Squalus suckleyi, is a commercially exploited shark species that plays an important role in the ecosystem. To elucidate the distribution of the SPD in the North Pacific and to evaluate the effects of sea surface temperature (SST) and prey availability on its distribution, we estimated the probability of SPD presence using a generalized additive model with a binomial error distribution from SPD presence/absence data on 14,824 operations in fishery‐independent gillnet surveys between 1972 and 2011. The habitat model was structured in the east and west to reflect differences in the North Pacific oceanic environments. In the east, a higher probability of SPD presence was identified along the coast from the eastern Gulf of Alaska to Queen Charlotte Sound. In the west, it was identified around northern Japan. The estimated distribution was continuous between the two areas, whereas the probability of SPD presence was relatively low. Although the probability of SPD presence was higher at SSTs between 6°C and 12°C, the SST at the peak probability of SPD presence differed between the west and east. The prey species, Japanese sardine, Sardinops melanostictus, and walleye pollock, Gadus chalcogrammus, in the west and boreal clubhook squid, Onychoteuthis borealijaponica, in the east significantly affected the probability of SPD presence, which was higher if the prey species co‐existed with SPD. Therefore, SPD might adapt their distribution to that of available prey species. SPD stock assessment and management in these two important areas are required for its sustainable utilization.     

Is pearl colour produced from Pinctada margaritifera predictable through shell phenotypes and rearing environments selections?

The black‐lipped pearl oyster, Pinctada margaritifera, is the most important farmed mollusc species in French Polynesia. Donor oyster selection among wild P. margaritifera individuals, chosen according to their inner shell colour, makes it possible to obtain the broadest range of cultured pearl colours of any species. This study demonstrates the relative influence of using black [B] or red [R] outer shell phenotypes, combined with green [G] or yellow [Y] inner shell phenotypes, on pearl darkness level, colour categories and lustre. A large scale grafting experiment was designed and carried out over five grow‐out locations, covering three archipelagos: Tuamotus, Society and Gambier. Results revealed that the [B + G] phenotypes may be used as donors to produce dark green pearl, which suit the demands of the Asian market; whereas, phenotypes incorporating [R] and/or [Y] phenotypes may be used to obtain multicolour pearls of medium/light darkness, which suit the demands of the European market. From an environmental point of view, the 1) [B] phenotype showed no significant variation for light and other pearl colour production, and 2) [Y] phenotype produced both the same rate of pearl darkness level and green colour pearls whatever the grow‐out location. A classification tree model was built to predict, according to shell phenotype and culture location, the colour and darkness level of harvested pearls. Lustre was shown to be more influenced by the environment than by phenotype. These results should be taken into account in pearl farm production management and in selective breeding programmes.     

Induction of larval metamorphosis in the sea cucumber Apostichopus japonicus by neurotransmitters

Larval metamorphosis inducers of the sea cucumber Apostichopus japonicus were screened from physiologically active compounds. Doliolaria larvae completed their metamorphosis to juveniles in 120 h when treated with 5–10 μM of dopamine and l-DOPA, and 50 μM of l-adrenaline and l-noradrenaline. Doliolaria larvae had to be exposed to dopamine or l-DOPA for at least 24 h. D1-like dopamine receptor antagonists SKF87566 and LE300 (10 μM) inhibited metamorphosis by dopamine. However, the D2-like dopamine receptor antagonists sulpiride and nemonapride (10 μM) did not inhibit the effect of dopamine. The results suggest that D1-like dopamine receptors are involved in larval metamorphosis of the sea cucumber A. japonicus.     

Seasonal distribution pattern of adult sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> (Stichopodidae) in Yoshimi Bay,western Yamaguchi Prefecture,Japan

To examine the distribution pattern of adult Apostichopus japonicus, approximately monthly surveys were conducted during a 2-year period in the subtidal zone of a harbor area in Yoshimi Bay, western Yamaguchi Prefecture. Results showed a clear seasonal change in distribution pattern: many animals were distributed on the seabed and the lower part of a jetty during winter to spring, whereas most animals occurred on the upper part of a jetty during summer to autumn, namely, the aestivation season. Such change is considered to be due to the migration of animals within the present study site. Y. Yamana is a Research Fellow of the Japan Society for the Promotion of Science.     

利用RCR-RAPD法和同功酶分析法日本柳杉无性系的识别方法研究

以日本福岛县林业试验场日本柳杉种子园的 ２４个无性系为材料,利用 ＰＣＲ—ＲＡＰＤ法和同功酶分析法对日本柳杉无性系的识别方法进行了比较研究。结果显示：同功酶法和由７个标记构成的ＲＡＰＤ分析法不能完全识别２４个无性系,用１７个和２７个标记构成的ＲＡＰＤ分析法识别这２４个无性系是可能的;同功酶标记是一种基因型标记,具有稳定性高的特点,适合于分析遗传构造的相似程度,特别适合于群体遗传分析,但是,由于能获得清晰话带的同功酶种类有限,在用于个体识别上比较困难;ＲＡＰＤ标记是一种显性标记,稳定性较差,但只要反应体系和条件稳定,利用ＲＡＰＤ标记正确进行无性系识别是完全可能的。     

DNA marker-assisted evaluation of potato genotypes for potential resistance to potato cyst nematode pathotypes not yet invading into Japan

One of major objectives of crop breeding is conferring resistance to diseases and pests. However, large-scale phenotypic evaluation for many diseases and pests is difficult because strict controls are required to prevent their spread. Detection of disease resistance genes by using DNA markers may be an alternative approach to select potentially resistant accessions. Potato (Solanum tuberosum L.) breeders in Japan extensively use resistance gene H1, which confers nearly absolute resistance to potato cyst nematode (Globodera rostochiensis) pathotype Ro1, the only pathotype found in Japan. However, considering the possibility of accidental introduction of the other pathotypes, breeding of resistant varieties is an important strategy to prevent infestation by non-invading pathotypes in Japan. In this study, to evaluate the prevalence of resistance genes in Japanese genetic resources, we developed a multiplex PCR method that simultaneously detects 3 resistance genes, H1, Gpa2 and Gro1-4. We revealed that many Japanese varieties possess not only H1 but Gpa2, which are potentially resistant to other pathotypes of potato cyst nematode. On the other hand, no genotype was found to have the Gro1-4, indicating importance of introduction of varieties having Gro1-4. Our results demonstrate the applicability of DNA-marker assisted evaluation of resistant potato genotypes without phenotypic evaluation.     

Effects of low-dose G-CSF formulation on hematology in healthy horses after long-distance transportation

The present study evaluated the effects of single-dose filgrastim on hematology in 16 healthy horses after long-distance transportation. Horses were assigned to receive filgrastim (0.23 µg/kg, SC, once; G-CSF group; n=8) or saline (0.9% NaCl) solution (0.3 ml, SC, once; control group; n=8) ≤ 1 hr before transportation. Horses were transported 2,530 km using commercial vans over the course of approximately 44 hr. Clinical examinations and hematologic analyses were performed on all horses before and after transportation. Because the post-transportation white blood cell counts and bacillary neutrophil to segmented neutrophil ratio were significantly higher in the G-CSF group, filgrastim may have promoted the mobilization of neutrophils from marrow. Filgrastim deserves a further study for efficacy in preventing horse shipping fever.