Contributions of salmon-derived nitrogen to riparian vegetation in the northwest Pacific region

We examined the relationship between the annual escapement of salmon and the δ ¹⁵N of willow (Salix spp.) leaves to evaluate the contribution of marine-derived nutrients (MDN) to riparian vegetation around the Pacific Northwest and Northeast regions. Foliar δ ¹⁵N values ranged from −3.42‰ to 4.65‰. The value increased with increasing density of carcasses up to 500 fish/km and 1500 fish/km. δ ¹⁵N values were variable at carcass densities below 500 fish/km. Possible factors affecting the fluctuation of δ ¹⁵N at reference sites are: (1) denitrification; (2) the presence of N₂-fixing trees, such as alder; and (3) agricultural runoff. δ ¹⁵N values at the sites with carcass densities over 500 fish/km were consistently high, while a value of δ ¹⁵N below zero was observed at only one site (Rusha River; δ ¹⁵N = −1.87‰). At this site, most adult pink salmon returned to limited locations near the estuary because steeper channel gradients acted as a migration barrier, resulting in the negative δ ¹⁵N value. Nevertheless, we concluded that our results showed evidence of the feedback of MDN to terrestrial vegetation, although the use of the δ ¹⁵N value as a terrestrial end member at spawning sites is limited. If the relationship between the enrichment index, which is expressed as the values using a mixing model, and salmon abundance was estimated, the availability of MDN in riparian ecosystems could possibly be evaluated and will lead to the establishment of escapement goals. An erratum to this article is available at .     

Scaling-up from tree to stand transpiration for a warm-temperate multi-specific broadleaved forest with a wide variation in stem diameter

Previous studies have demonstrated a clear relationship between diameter at breast height (DBH) and tree transpiration (Q _T) in multi-specific broadleaved forests. However, these studies were conducted with a limited range of tree sizes and species, and thus many multi-specific broadleaved forests fall outside these conditions. Therefore, this study examined the relationship between DBH and Q _T in a warm-temperate multi-specific broadleaved forest (n = 12 species) with a wide range of tree sizes (5.0–70.0 cm DBH) using the Granier-type heat dissipation method. The results showed that, although sap flow density varied between individual trees and species, there was a significant relationship between log Q _T and log DBH (r ² = 0.66, P < 0.001) because of the strong dependence of sapwood area on DBH. This study confirmed the applicability of the relationship for the stand transpiration (E _C) estimates even in a multi-specific broadleaved forest with a wide variation in DBH. Our results also revealed that selecting the sample trees in descending order of DBH effectively reduced potential errors in E _C estimates for a specific sample size, as larger trees contribute more to E _C. This information should be useful for future studies investigating the transpiration of multi-specific broadleaved forests, reducing errors during the scaling-up procedure.     

Hybrid aspen with a transgene for fungal manganese peroxidase is a potential contributor to phytoremediation of the environment contaminated with bisphenol A

To assess the possible utility of a fungal gene for manganese-dependent peroxidase (MnP) produced by a transgenic plant in phytoremediation, we transformed hybrid aspen with a chimeric gene for MnP. Our gene construct allowed expression of the gene for MnP in plants and relatively high MnP activity was detected in the hydroponic medium in which roots of plants that expressed the transgene had been cultured. Some of our transgenic plants were able to remove bisphenol A from the medium more efficiently than wild-type plants. Our results demonstrate that, without any modification of the coding sequence, a chimeric gene for fungal MnP can be expressed in a woody plant, with secretion of active MnP from roots into the rhizosphere. Our strategy suggests new options using woody plants for phytoremediation.     

Pathological Findings in a Case of Equine T-Cell Lymphoma Associated with Ataxia

A 15-year-old Dutch Warmblood gelding suddenly developed incoordination and hindlimb stumbling. The horse had a history of eyelid lymphoma. Necropsy revealed yellow-white or dark reddish-brown masses adhering to the outer surface of the spinal dura mater from the first cervical vertebra to the seventh thoracic vertebra. The spinal cord close to the first cervical vertebra and the seventh thoracic vertebra was markedly compressed by the masses filling the epidural space. The masses were also observed in the larynx, eyelids, and adipose-rich tissues, including the joints and orbits. They appeared similar in shape. The mandibular, retropharyngeal, axillary, superficial inguinal, deep inguinal, and lateral iliac lymph nodes were solid and enlarged. Histologically, the masses were composed of small or medium-sized lymphocyte-like tumor cells, but atypical cells and mitotic figures were rare. There were moderate infiltrations of macrophages and multinucleated giant cells, which were occasionally ingesting the surrounding tumor cells. Immunohistochemically, the tumor cells were classified as T-cell-derived cells. Throughout the spinal cord, enlargement or loss of nerve axons, dilation of periaxonal spaces, and macrophage infiltration into periaxonal spaces were observed, mainly in the ventral funiculus. Spinal cord compression by the tumor mass was suggested as a cause of the locomotive dysfunction. This is the first report of equine lymphoma with ataxia located from the proximal cervical to middle thoracic dura mater and in joint cavities.     

Clinical significance of plasma mannose concentrations in healthy and diabetic dogs

Circulating levels of monosaccharides can act as a reflection of systemic glucose/ energy metabolism. Characteristic changes observed in these levels can be seen in patients with diabetes and other metabolic disorders. There have been a few reports describing the significance of mannose metabolism as an energy source under physiological and pathological conditions. However, the relationship between circulating levels of mannose and the pathophysiology of diabetes mellitus are unknown in dogs. This study examined circulating levels of mannose between healthy control and diabetic dogs and evaluated the clinical significance of mannose levels in dogs. Diabetic dogs demonstrated a higher circulating level of mannose in comparison to normal healthy control dogs. Plasma mannose was positively correlated with plasma glucose and fructosamine, respectively. Interestingly, plasma mannose levels were affected by plasma insulin levels. In the context of feeding and glucose tolerance tests, plasma mannose levels responded to changes in circulating insulin levels. Circulating plasma mannose levels decreased after feeding in both control and diabetic animals in spite of observed insulin level differences. However, when glucose tolerance tests were given, a positive correlation between mannose levels and insulin levels was observed. Therefore, plasma mannose levels obtained via glucose tolerance testing may be used as a new diagnostic method for evaluating insulin resistance or deficiency in diabetic dogs.     

A practical formula for quantifying the thermal conductivity of Tottori dune sand

Abstract

Sustainable agriculture needs appropriate management of water, chemicals and heat in soil. In this study, we focused on thermal conductivity, which is among the various soil physical properties that are crucial for the sustainable management of agricultural fields. To expand the Mochizuki model, which describes thermal conductivity as a function of water content and solution concentration, we considered the water content, solution concentration and temperature as independent variables. The thermal conductivity of Tottori dune sand was measured under conditions of various combinations of these three independent variables. We observed that the thermal conductivity increased linearly with increasing water content, 0.054–0.276 m³ m^?3, for fixed temperature and solution concentration, and varied linearly with solution concentration for fixed temperature and water content. These results are consistent with the Mochizuki model. Using the Mochizuki model, the experimental parameters, which are dependent variables of water content and solution concentration, are shown as functions of water content. From regression analyses of the relationships between the experimental parameters and temperature, we expanded the Mochizuki model into a new practical formula that quantifies the soil thermal conductivity as a function of water content, solution concentration and temperature.     

First case report of Sarcocystis neurona-induced equine protozoal myeloencephalitis in Japan

Equine protozoal myeloencephalitis developed in a three-year-old male Thoroughbred racehorse imported from the United States. The animal showed astasia five days after the onset of ataxia. Histopathologically, focal nonpurulent myelitis accompanied by hemorrhage and perivascular infiltration was observed in the fourth and fifth cervical spinal cord. Immunohistochemically, shizonts were occasionally observed and were positive for anti-Sarcocystis neurona (S. neurona) antiserum. S. neurona-specific antibodies were detected in the serum and cerebrospinal fluid by Western blot. This is the first equine protozoal myeloencephalitis case in Japan.     

A gross and histopathological study of an ectopic white line development in equine laminitis

In horses with chronic laminitis, an abnormal horny structure called lamellar wedge, is generated between the hoof wall and the laminar epidermis. To be able to manage horses with chronic laminitis correctly, more information about the pathological state of this abnormal horn is required. The aim of this study was to collect and analyze objective morphological data about the abnormal horn in order to understand its morphology and development. In the study, the abnormal horn was grossly visible on the sagittal hoof section from approximately 20 days after the onset of disease. In the histological observations, the structural characteristics of this abnormal horn were similar to the white line tissue, suggesting it is an ectopic white line. Mean value of the cross-sectional area of the abnormal horn against the distal phalanx section area (A/D) was 0.29 cm(2) SD +/- 0.14 and it finally showed an eight-fold increase over the mean value of normal white line section area against the distal phalanx section area. In conclusion, a large amount of the ectopic white line is thought to be finally able to inhibit normal hoof wall growth, so that it should be resected at the optimum time when would be after one month from the onset of the disease.     

Sex identification of Japanese black bear,Ursus thibetanus japonicus,by PCR based on amelogenin gene

A method for sex identification of the Japanese black bear was examined using a polymerase chain reaction (PCR) and sequencing of a part of the amelogenin gene. This gene is located on the X and Y chromosomes, and there are 54 nucleotide deletions on the Y chromosome-specific gene. Forty-seven (26 male and 21 female) DNA samples and 23 (13 male and 10 female) DNA samples, respectively extracted from white blood cells and hairs of Japanese black bears were analyzed. The primers SE47 and SE48 from this X-Y homologous region were used in sex identification by PCR amplification. These primers amplified X- and Y-specific bands, which could be used to discriminate between sexes by a length polymorphism in all samples. We suggest that PCR amplification using the primers SE47 and SE48 is useful for sex determination of the Japanese black bear and could be applied to DNA analysis of small samples such as hairs.     

Sequences of canine glutamate decarboxylase (GAD) 1 and GAD2 genes, and variation of their genetic polymorphisms among five dog breeds

Glutamate decarboxylase (GAD) is the primary enzyme in the brain that catalyzes the synthesis of gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter. There are two isoforms named according to their molecular weights, GAD67 and GAD65, which are encoded by GAD1 and GAD2, respectively. To investigate the association between GAD genes and temperament in domestic dogs, Canis familiaris, we sequenced the full lengths of the coding regions of these genes and identified three single nucleotide polymorphisms (SNPs) in GAD1 and one in GAD2. When comparing genotype and allele frequencies of SNPs among five breeds with different behavioral traits, statistically significant interbreed differences were observed for three SNPs in GAD1. These results suggest that GAD1 SNPs may be useful for behavioral genetic studies in dogs.