Patterns of shoot mortality in Betula platyphylla in northern Japan

To understand the development of crown structure in Betula platyphylla Sukatch., mortality patterns of long shoots were analyzed quantitatively. We selected 25 saplings growing under various light conditions and measured the relative photosynthetically active radiation (rPAR) at, and the three-dimensional position of, first-order branches. A long shoot was assigned "no buds" (NB) status if it lacked buds at the end of the growing season, including at the tips of short shoots. A long shoot was classified as dead if it was NB and all the offspring long shoots issuing from it were NB. The probability that a leafy long shoot (a current-year long shoot with leaves or an older long shoot with short shoots with leaves) would become NB by the end of the season was positively dependent on shoot age and branch age, and negatively dependent on shoot length, centripetal shoot order, branch height and rPAR at the branch. Randomization tests revealed that shoots became NB and dead in clusters of connected shoots. In particular, shoot clusters originating from 3-year-old shoots were more likely to die than expected if each shoot was assumed to become NB regardless of the connection. Stepwise logistic regression revealed that the maximum rPAR within the crown of an individual tree had a significant effect on the mortality rate of 3-year-old shoot clusters, together with the rPAR at the level of the branch and other structural entities. Correlative inhibition is an important mechanism for determining shoot mortality patterns.     

Changes in circulating adiponectin and metabolic hormone concentrations during periparturient and lactation periods in Holstein dairy cows

Although our previous report demonstrated that adiponectin and AdipoR1 gene expressions changed among different lactation stages in the bovine mammary gland, its in vivo kinetics remain unclear in ruminant animals. In this study, we investigated the changes in circulating concentrations of adiponectin, as well as other metabolic hormones and metabolites, (i) during the periparturient period and (ii) among different lactation stages, in Holstein dairy cows. In experiment 1, serum adiponectin concentrations increased after parturition. Serum insulin concentrations were lower in the postpartum than prepartum period, whereas serum growth hormone (GH) concentrations increased in the postpartum period. Serum nonesterified fatty acids (NEFA) levels were increased during the postpartum period and were dependent on the parity. In experiment 2, there was no significant difference in plasma adiponectin concentrations among lactational stages. Plasma insulin concentrations tended to be lower in early lactation while plasma GH levels tended to be higher. Plasma NEFA concentrations were significantly lower in mid‐ and late‐lactation stages than non‐lactation stages. These findings indicate that elevation of serum adiponectin might be involved in energy metabolism just around parturition, and might exert its action through regulation of receptor expression levels in target tissues in each lactational stage in Holstein dairy cows.     

Association of the amino acid motifs of BoLA-DRB3 alleles with mastitis pathogens in Japanese Holstein cows

The association of the polymorphism of bovine leukocyte antigen ( BoLA-DRB3 ) genes, identified by the polymerase chain reaction sequence-based typing (PCR-SBT) method, with resistance and susceptibility to mastitis caused by Streptococci , coagulase-negative Staphylococci, Escherichia coli and Staphylococcus aureus was investigated. Blood samples for DNA extraction were collected from 170 Holstein cows (129 mastitis and 41 healthy cows) from 5 districts in Chiba prefecture, Japan. Susceptibility or resistance to the mastitis-causing pathogens was thought to vary by the presence of amino acid substitutions at the 9, 11, 13, and 30 positions. DRB3*0101 and DRB3*1501 had amino acid motifs of Glu⁹, Ser¹¹, Ser¹³, and Tyr³⁰, and they were considered to have susceptibility to all 4 mastitis pathogens. In contrast, DRB3*1101 and DRB3*1401 had amino acid motifs of Gln⁹, His¹¹, Gly¹³, and His³⁰ in these positions, and they also had Val⁸⁶, so these alleles were considered to have resistance to Streptococcal and coagulase-negative Staphylococcal mastitis. However, in the case of Escherichia coli mastitis, amino acid substitutions at the 9, 11, 13, and 30 positions had little effect, but rather substitutions at the 47, 67 positions of pocket 7, and at the 71, 74 positions of pocket 4, Tyr⁴⁷, Ile⁶⁷, Ala⁷¹, and Ala⁷⁴, were associated with resistance. This motif was present in DRB3*1201 .     

Effects of ruminal dosing of mechanical stimulating brush on digestibility and rumen fermentation status in Holstein steers fed low rice straw at different lengths

The objectives of the present study were to determine the effect of ruminal dosing of mechanical stimulating brush (Rumen faibu; RF) on digestibility and on rumen fermentation status in Holstein steers fed high concentrate and low rice straw. Eight steers (461 kg in average bodyweight) were used. Four steers were orally dosed three RF per head (RF‐dosing) and the other four were not dosed (non‐RF). All steers were fed enough concentrate and rice straw to gain 1.4 kg/day in bodyweight. Rice straw was cut 2 cm and 30 cm. The organic cell wall content of feeding diets was 17% in dry matter basis. Digestibility and nutritive value were not affected by RF dosing and length of rice straw. Ruminal pH was significantly lower in RF‐dosing group than in non‐RF group after feeding, and tended to be higher in long rice straw than in short rice straw throughout the day. There were no clear difference on total volatile fatty acid concentration and molar proportion of volatile fatty acid by RF dosing and length of rice straw throughout examined period. These present results suggest that digestibility and rumen fermentation status are not affected by RF dosing when organic cell wall content of feeding diets is approximately 17% in dry matter with rice straw over 2 cm.     

Effects of supplementary corn silage on the feed intake and milk production of time-restricted grazing dairy cows

The effects of supplementary corn silage (CS) of either 2 or 4 kg of dry matter (DM; S + 2 and S + 4, respectively) above the energy requirement for milk production and maintenance for grazing dairy cows (S) were determined. Time‐restricted grazing was used to compare the feed intake, milk production, and nitrogen and energy use of lactating cows. The experiment was carried out on two different pastures using a 3 × 3 Latin square design for each pasture. Cows were grazed for 5 h on a rotational grazing system and were fed concentrate (1 kg per 5 kg of milk yield). Herbage intake was measured using a weighing technique. To calculate the energy and nitrogen use, whole feces and urine were collected. There was no statistical effect of the pastures. Herbage intake decreased by the addition of CS (P = 0.02). The reduction of herbage DM intake per unit consumption of supplementary CS towards the S group were 0.80 and 0.45 kg for the S + 2 and S + 4 groups, respectively. The total DM intake for the S + 4 group was higher than that for the S and S + 2 groups (P = 0.02). Milk yield did not differ among treatments, even though the total DM intake for the S + 4 group was higher than that of the S and S + 2 groups. Nitrogen and energy use did not differ with the addition of CS.     

Successful use of prednisolone and radiation therapy in a dog with intracranial histiocytic sarcoma

The ideal treatment for intracranial histiocytic sarcoma (HS) remains unclear. Herein, we report a case of intracranial HS that was successfully treated using prednisolone and radiation therapy. The patient was a 9-year-old spayed female Pembroke Welsh Corgi that presented with epileptic seizures. Magnetic resonance imaging revealed a contrast-enhancing mass adjacent to the right piriform lobe. Prednisolone administration (1 mg/kg/day) decreased the lesion size. Additional palliative radiation therapy (total dose, 37 Gy) resulted in complete disappearance of the lesion. However, on day 164, the dog’s neurological signs deteriorated, and she was euthanized. Necropsy revealed an intracranial metastasis of HS via the cerebrospinal fluid without any extracranial metastasis. Nonetheless, combined prednisolone and radiation therapy might be effective in treating intracranial HS.     

Age-related changes in contractions of chicken aorta and ischiadic artery

The characteristics of the contraction of vascular smooth muscle were examined in thoracic aorta and ischiadic artery of chickens aged 3, 6, 10 and 18 weeks. High K⁺ solution induced a sustained contraction in smooth muscle preparations of aorta and ischiadic artery in vitro . The contraction of the ischiadic artery became greater with age, whereas the contraction of the aortic preparation did not. In the ischiadic artery, the magnitude of the contraction divided by the weight of the muscle preparation was constant at all ages studied. However, those in the aortic preparation decreased with age. These results suggest that the changes in the contractile responses of vascular smooth muscle owing to the age of chickens vary widely according to the preparations of blood vessels, and that the functional smooth muscle cells in the thoracic aorta of chicken do not increase with age.     

孝昌马尾松天然林同工酶遗传构造的分析研究

通过对湖北省孝昌县小悟乡的马尾松（Ｐｈｕｓ ｍａｓｓｏｎｉａｎａ）天然林的针叶进行的同工 酶实验,６种酶系统的１１个基因位点得到了确认。以各基因位点上的等位基因的频率为基础, 对该林分内部的遗传变异进行了研究,结果表明,该林分具有较高的遗传变异性,其多态位点 百分率（ＰＩ）为９０．９％、等位基因平均数（Ｎａ）为３．１８、有效等位基因（Ｎｅ）为１．９１、平均期待杂 合率（Ｈｅ）为０．４２、近交系数（Ｆｉｓ）为０．３３,且存在不同基因位点间高频率的连锁不平衡。同时 将马尾松个体间的距离分成不同的等级,考察各等位基因频率的变化情况（Ｍｏｒａｎ’ｓＩ和ＳＮＤ 曲线的变化规律）,进一步对该林分内的遗传构造和林分的成立过程进行了研究和探讨,发现 其邻域的大小为１０～１２ｍ。在此基础上提出了对该类的天然林的遗传资源保存的对策。     

A Variant of Cucumber mosaic virus Is Restricted to Local Lesions in Inoculated Tobacco Leaves with a Hypersensitive Response

A variant of Cucumber mosaic virus, CMV(Y/GM2), was isolated from a tobacco plant with mild green mosaic symptoms that was regenerated in vitro from a yellow strain of CMV [CMV(Y)]-infected tobacco leaves by tissue culture. CMV(Y/GM2) has two amino acid substitutions at 36 and 111 positions in the coat protein encoded on RNA3. CMV, assembled by mixing in vitro transcribed CMV(Y) RNA1 and RNA2 plus infectious RNA3 transcribed in vitro from cDNA to RNA3 of CMV(Y/GM2), was prepared and designated as CMV(Y/GM2)tr. When tobacco (Nicotiana tabacum cv. Xanthi nc) plants were inoculated with CMV(Y/GM2)tr, large necrotic local lesions in which the virus was localized, developed on the inoculated leaves. This host response unique to CMV(Y/GM2)tr was similar to the hypersensitive response (HR), which is a common resistance response to avirulent pathogens and was observed in five cultivars of Nicotiana tabacum and eight Nicotiana species. The revertant virus, however, accumulated to quite different levels in the various hosts. CMV(Y/GM2)tr induced pathogenesis-related 1 (PR-1) protein accumulation and systemic acquired resistance (SAR) which were generally observed in the HR. However, when tobaccos were inoculated with CMV(S36P)tr and CMV(V111I)tr, which have an amino acid substitution at either the 36 or 111 position in the coat protein of CMV(Y), respectively, CMV(S36P)tr was restricted to the primary infection site without necrotic local lesion formation and PR-1 protein and SAR induction. CMV(V111I)tr, however, systemically spread and induced mild green mosaic symptoms, while the host had the HR to CMV(Y/GM2)tr. The localization of CMV(Y/GM2)tr at the primary infection site may not only be caused by the HR, but also by the restriction of virus systemic movement resulting from the amino acid substitution at position 36 in the coat protein of CMV(Y). Received 15 December 1999/ Accepted in revised form 18 April 2000