Acoustic evaluation of the vertical distribution of dwarf ayu Plecoglossus altivelis altivelis in Lake Biwa

SUMMARY: The vertical distribution of dwarf ayu Plecoglossus altivelis altivelis in the pelagic waters of Lake Biwa was evaluated from June to September in 1995–97 from eight acoustic surveys using a quantitative echosounder. In each survey, echoes from a depth range of 3 m to the sea bottom were collected at a station every 2.7 s for 24 h together with measurements of vertical profiles of water temperature and chlorophyll-a. The ayu's echoes were identified using an underwater video camera. The ayu were observed near the maximum chlorophyll-a depth and above the thermocline. Their density was highest at depths of 4–11 m with 2–4 individuals/m ³ and was almost zero below 20 m. Echo signs were recorded as having a frequent duration of more than 1 h at night, whereas were of a shorter duration in the day. The fish stay in the epilimnion during the day without any clear vertical migration, but are distributed more uniformly at night. The advantages of remaining in the epilimnion are discussed in terms of food availability and predator avoidance.     

Influence of ventral fixation techniques on atlantoaxial joint fusion in canine models with dens partial resection

We evaluated the completeness of bony fusion of the atlantoaxial joint (AAJ) through polymethylmethacrylate fixation (PMF) and atlantoaxial plate fixation (APF) using six canine models with dens partial resection. In both groups, the hydroxyapatite content at the AAJ was measured up to 7 months postoperatively using quantitative computed tomography. Histological assessment revealed fibrous fusion in the PMF group. Meanwhile, in the APF group, only one dog achieved fibrous fusion, whereas the remaining three showed bony fusion. To our knowledge, this study was the first to evaluate AAJ fusion histologically after PMF and APF. The present study demonstrates that PMF and APF may stabilize the AAJ without clinical complications. Therefore, PMF and APF are clinically useful fixation methods for atlantoaxial instability.     

A 10-year survey of antimicrobial susceptibility of streptococcus suis isolates from swine in Japan

A number of 689 Streptococcus suis isolates collected nationwide from diseased and healthy pigs from 1987 to 1996 were surveyed for antibiotic susceptibilities to 11 drugs. No isolates resistant to amoxicillin, chloramphenicol, and sulfamethoxazole/trimethoprim were found. Isolates were highly susceptible to penicillins (penicillin G, ampicillin, and amoxicillin) except cloxacillin. They were not susceptible to tetracycline, streptomycin, and kanamaycin (MIC90 50 microg/ml, > or = 100 microg/ml, and > or = 100 microg/ml, respectively). Multiple-resistant isolates (> or = 3 antimicrobial agents) were found in 20.3% of all isolates tested.     

A novel repeated sequence located on the bovine Y chromosome: its application to rapid and precise embryo sexing by PCR

A novel repeated sequence specific to male cattle was identified and named S4. S4 is a highly repetitive sequence and is a 1.5 kb repeating unit that contains various internal repeated sequences. FISH analysis showed that S4 is localized on the whole long arm and the proximal region of the short arm of the Y chromosome. We found that a PCR primer set for S4 amplified a male-specific 178 bp product in addition to a 145 bp product common to both male and female cells. Although the origin of the 145 bp product is unknown, it acts as a positive internal control in practical embryo sexing. Due to the high copy number of S4, PCR required only 0.5 pg purified DNA for accurate amplification. This made it possible to reduce the amount of biopsy sample required for embryo sexing and thus result in less damage to embryos manipulated. These studies indicate that embryo sexing based on the S4 sequence is accurate and sensitive.     

Direct and indirect markers of cartilage metabolism in synovial fluid obtained from dogs with hip dysplasia and correlation with clinical and radiographic variables

OBJECTIVE: To compare activities of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and matrix metalloproteinase (MMP)-3 and contents of sulfated glycosaminoglycan (S-GAG) in joint fluid obtained from dogs with hip dysplasia (HD) and clinically normal dogs, evaluate correlations among these markers in joint fluid obtained from dogs with HD, and evaluate correlations between each marker and clinical and radiographic variables. Animals-26 dogs with HD (clinical group) and 43 clinically normal Beagles (control group). PROCEDURE: Joint fluid was aseptically collected from the hip joints of all dogs. For each dog in the clinical group, age, duration of lameness, radiographic osteoarthritis (OA) score, and Norberg angle in each affected joint were recorded. Activities of IL-1beta, IL-6, TNF-alpha, and MMP-3 and S-GAG contents were measured. Values were compared between groups by use of Mann-Whitney U tests, and the Spearman rank correlation test was used to evaluate correlations among markers and between each marker and clinical or radiographic variables. RESULTS: Values of all markers were significantly higher for the clinical group, compared with values for the control group. There was a moderate positive correlation between lameness duration and IL-6 activity and a strong negative correlation between the Norberg angle and IL-1beta activity. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of our results indicated that there was a significant increase in markers of OA in dogs with HD. Activities of IL-1beta and IL-6 in joint fluid of dogs with HD may be influenced by the severity of laxity in the hip joint and lameness duration, respectively.     

Incidence of silent ovulation in dairy cows during post partum period

The present study was undertaken to show the incidence of silent ovulation in high producing dairy cows, by monitoring ovarian cyclicity based on practical milk progesterone assay which was established in this study. The direct milk progesterone enzyme linked immunosorbent assay (ELISA) was developed using anti-progesterone-3(E)-carboxymethyloxime-BSA antibody for the antibody and horse radish peroxidase labeled progesterone for tracer. High sensitivity (26 pg/mL, 0.65 pg/well), high recovery rates (83-97%), high reproducibility (CV of intra-assay 4.8-11.5%; CV of inter-assay 14.3-19.1%) and high correlation between milk progesterone concentrations measured by the direct ELISA and the values obtained by the ELISA after extraction proved the reliability of the assay. In second experiment the incidence of silent ovulation was investigated based on the milk progesterone concentrations in 32 dairy cows within 70 days post partum. The incidences of silent ovulation at the first, second, third and fourth ovulation post partum were 83, 46, 13 and 0%, respectively. Most commonly observed patterns of sequential occurrence of silent ovulation in cows ovulating 2, 3 or 4 times within 70 days post partum were silent-estrus (50%), silent-silent-estrus (60%) and silent-silent-estrus-estrus (67%), respectively. These results suggest that the present ELISA is a reliable and practically applicable method for determination of progesterone in milk and that high producing dairy cows show a high incidence of silent ovulation at the first post partum ovulation as well as the second ovulation, which then decreased with the increased frequency of ovulation.     

Functional anatomy of the ocular circulatory system: vascular corrosion casts of the cetacean eye

OBJECTIVE: To examine the functional anatomy of the ocular circulation in four bottlenose dolphins (Tursiops truncatus) and five melon-headed whales (Peponocephala electra). PROCEDURE: Eyes were obtained postmortem from whales that died while in captivity and/or were found beached. Specimens from whales were investigated using scanning electron microscopy (SEM) of vascular corrosion casts and histology. The thermal characteristics of live dolphin eyes were measured using an infrared imaging system. RESULTS: The whale eye receives its primary blood supply from the ophthalmic rete, which extends just behind the eyeball. The ophthalmic rete diverges from the basilar rete and the cervical rete via the posterior thoracic artery. The iris and ciliary processes are supplied by iridic arteries via the major arterial circle that is located around the iris edge. The retinal vessels show the holangiotic type. Choroidal arteries run in parallel arrays so as to interdigitate the densely packed choroidal veins. The venules in the conjunctival fold and palpebral conjunctiva form a well-developed venous plexus. Thermographic examination revealed that the eye shows a substantially higher degree of thermal emission than adjacent skin areas. CONCLUSIONS: The cetacean eye is characterized by a unique vascular pattern and multivessel plexuses, which are quite different from those of terrestrial mammals. This suggests that the ocular vasculature might function as a thermoregulatory system so that the appropriate operating temperature for the photoreceptors can be maintained in a deep and cold aquatic environment. The distinctive plexuses in the orbit might also be for pooling blood in the eye to conserve oxygen during dives. The ophthalmic rete might play a role in a pressure-damping effect on cetacean ocular circulation as well.     

Plasma Progesterone Profile in Ovariectomized Beef Cows after Intra-vaginal Insertion of New, Once-used or Twice-used CIDR

Objective of this study was to show plasma progesterone concentrations in ovariectomized beef cows after treatment with new, once-used and twice-used controlled internal drug-releasing devices (CIDRs). Four ovariectomized beef cows were used for the experiment. Plasma concentrations of progesterone were quantified using a validated ELISA. The CIDR was inserted into vagina of cows by using a standard CIDR applicator and then removed 7 days after insertion. One week later, once-used CIDR was inserted and removed on day 7. Twice-used CIDR was, then inserted at an interval of 7 days. Mean plasma concentrations of progesterone 24 h after new CIDR insertion was 4.0 ± 0.1 ng/ml, which thereafter decreased gradually to 1.4 ± 0.1 ng/ml at day 7. In cows treated with once-used CIDR or twice-used CIDR, mean plasma progesterone concentrations at day 1 were 2.4 ± 0.2 or 1.8 ± 0.2 ng/ml and 1.0 ± 0 or 0.9 ± 0.1 ng/ml at day 7 respectively. The results suggest that once-used CIDR may be still effective to produce luteal phase progesterone concentrations in plasma in non-suckling beef cows.     

Effect of calf death loss on cloned cattle herd derived from somatic cell nuclear transfer: Clones with congenital defects would be removed by the death loss

To increase public understanding on cloned cattle derived from somatic cell nuclear transfer (SCNT), the present review describes the effect of calf death loss on an SCNT cattle herd. The incidence of death loss in SCNT cattle surviving more than 200 days reached the same level as that in conventionally bred cattle. This process could be considered as removal of SCNT cattle with congenital defects caused by calf death loss. As a result of comparative studies of SCNT cattle and conventionally bred cattle, the substantial equivalences in animal health status, milk and meat productive performance have been confirmed. Both sexes of SCNT cattle surviving to adulthood were fertile and their reproductive performance, including efficiency of progeny production, was the same as that in conventionally bred cattle. The presence of substantial equivalence between their progeny and conventionally bred cattle also existed. Despite these scientific findings, the commercial use of food products derived from SCNT cattle and their progeny has not been allowed by governments for reasons including the lack of public acceptance of these products and the low efficiency of animal SCNT. To overcome this situation, communication of the low risk of SCNT technology and research to improve SCNT efficiency are required.