BRAIN MAGNETIC RESONANCE IMAGING CHARACTERISTICS IN DOGS AND CATS WITH CONGENITAL PORTOSYSTEMIC SHUNTS

Animals with a portosystemic shunt (PSS) often have neurologic abnormalities. Diagnostic imaging, including brain magnetic resonance (MR) imaging, is not performed routinely in these animals. In this study, brain MR images were obtained in 13 dogs and three cats with a PSS, and in 15 dogs and five cats that were neurologically normal and used as controls. All animals with a PSS had widened sulci. In addition, 10 out of 13 dogs with a PSS and one out of three cats with a PSS had hyperintense focal areas in the lentiform nuclei on T1-weighted (T1W) images, which did not enhance after intravenous gadolinium. Following surgical correction of the PSS, MR imaging examinations were repeated in one dog and one cat. The hyperintensity of the lentiform nuclei had decreased. This study indicates that MR imaging findings of widened sulci and hyperintensity of the lentiform nuclei on T1W images may be found in dogs and cats with a PSS.     

Genetic relationship between Echinochloa crus‐galli and Echinochloa oryzicola accessions inferred from internal transcribed spacer and chloroplast DNA sequences

Barnyardgrass, hexaploid Echinochloa crus‐galli, is considered to arise from the hybridization between tetraploid Echinochloa oryzicola and an unknown diploid species. The genetic relationship between E. crus‐galli and E. oryzicola was examined to investigate the position of E. oryzicola in the evolutionary process of E. crus‐galli, based on the nuclear DNA internal transcribed spacer (ITS) and the chloroplast cpDNA trnT‐L, trnL intron, and trnL‐F regions. New World E. crus‐galli was clearly separated from Eurasian E. crus‐galli and showed a close relationship to the American taxa, Echinochloa crus‐pavonis and Echinochloa walteri, in both the ITS and chloroplast DNA. The nrDNA ITS sequences indicated no differentiation between the Eurasian E. crus‐galli and E. oryzicola, in contrast to their clear divergence in the cpDNA sequence. The present results suggest that E. oryzicola is the male donor of E. crus‐galli.     

CLINICAL MAGNETIC RESONANCE VOLUMETRY OF THE HIPPOCAMPUS IN 58 EPILEPTIC DOGS*

Hippocampal atrophy, which is a component of hippocampal sclerosis and recognized commonly in human intractable epilepsy, is controversial in canine epilepsy. We examined the hippocampal volume in 58 epileptic dogs and 35 control dogs using magnetic resonance (MR) images, and calculated the relative hippocampal volume asymmetry of the right and left hippocampus. Subjectively, there were visible MR imaging abnormalities in seven of the 58 epileptic dogs (12%). The hippocampel volume asymmetric ratio of epileptic dogs (5.84±4.47%) was significantly greater than that of control dogs (1.62±0.88%). Using a cutoff threshold asymmetric ratio of 6% that is indicated in human epilepsy, 28 epileptic dogs (48%) were characterized as having unilateral hippocampus atrophy. The hippocampal volume asymmetry ratio cannot be used to detect bilateral atrophy. In conclusion, although less frequent than that observed in human epilepsy patients, hippocampal atrophy may occur in canine epilepsy.     

MEASUREMENT OF INTERTHALAMIC ADHESION THICKNESS AS A CRITERIA FOR BRAIN ATROPHY IN DOGS WITH AND WITHOUT COGNITIVE DYSFUNCTION (DEMENTIA)

The criteria for brain atrophy in dogs have not yet been established, because of wide variation in the morphology of the ventricles and sulci of the brain depending on the breed and size. In this study, we examined the thickness of the interthalamic adhesion in a transverse magnetic resonance image to investigate normal, to examine the correlation with age, body weight, and breed, and to assess whether measurement would be a useful indicator of brain atrophy. The animals used in this study were of various breeds and weight, and had no identifiable intracranial lesion. They were divided into two groups: a normal group (0.6-15-year-old, n = 66) and a demented aging group (12-18-year-old, n = 12). The interthalamic adhesion thickness in both T1- and T2-weighted transverse images were measured in all dogs. The interthalamic adhesion thickness in the normal and demented groups was 6.79 +/- 0.70 and 3.82 +/- 0.79 mm, respectively. The interthalamic adhesion thickness in the demented group was significantly smaller. In an analysis of the correlation of interthalamic adhesion thickness with age and weight in normal dogs, significant negative and positive correlation was recognized, respectively. However, the strength of these correlations was low. These results suggest that interthalamic adhesion thickness may be a good parameter for evaluating brain atrophy in dogs with cognitive dysfunction.     

Marine biogeochemical response to a rapid warming in the main stream of the Kuroshio in the western North Pacific

Impact of climate change on marine biogeochemical parameters and ecosystem is one of the important issues of our environment. Direct evidence of marine pelagic ecosystem changes is found with warming of sea water and sea‐level rise in the main stream of the Kuroshio in the East China Sea and the western North Pacific during these three decades based on the analysis of long‐term comprehensive hydrographic observations. In terms of annual mean, the warming rate of surface air temperature and sea surface temperature ranged from 0.15 to 0.21°C per decade in and around the main stream of the Kuroshio in the East China Sea, which exceed the global mean warming rate of 0.128 ± 0.026°C per decade during the period from 1956 to 2005 reported in IPCC 2007. One of the features in this rapid warming region is an increase of number of Pterosagitta draco, a cosmopolitan warm‐water zooplankton. Biogeochemical parameters, such as wet weight of zooplankton, plant pigment and nutrients concentration in the upper 200 m have been decreasing while dissolved oxygen content and seawater temperature have been increasing in the upper 200 m in the main stream of the Kuroshio in the East China Sea. These observed linear trends of the biogeochemical parameters would be foresights for temperate oceans in the future.     

A modeling approach to evaluate growth and movement for recruitment success of Japanese sardine (Sardinops melanostictus) in the western Pacific

A two‐dimensional individual‐based fish movement model coupled with fish bioenergetics was developed to simulate the observed migration and growth of Japanese sardine (Sardinops melanostictus) in the western North Pacific. In the model, derived from the observed ocean–environmental data as the driving force, fish movement was adapted as a kinesis behavior. The model successfully simulated the observed transport patterns during the egg and larval stages and the northward migrations during the juvenile stage in 2005, 2006 and 2007. The model results showed that both temperature during the larval stage in the Kuroshio Extension and the prey availability during the early juvenile stage in the Kuroshio–Oyashio transitional area are important factors for growth of Japanese sardine. In autumn, the observed juvenile sardine were mainly distributed in the subarctic water region off the Kuril Islands, which is an area (158–165°E, 43–47°N) with a high chlorophyll‐a (Chl‐a) concentration. The model reproduced the fish distribution, which has a high density in this region. The high Chl‐a concentration area in autumn may contribute to increasing the survival rate of Japanese sardine by cascading up the food chain, from the high primary production, and is an important habitat for recruitment success of Japanese sardine.     

Oryza sh4 gene homologue represents homoeologous genomic copies in polyploid Echinochloa

The coding region sequence of the Oryza sh4 gene homologue in Echinochloa was analyzed in relation to the shattering nature of spikelets and the phylogeny of homologue copies in the Asian annual polyploidy Echinochloa . The Sh4 homoeologue copies were detected in Echinochloa oryzicola , Echinochloa crus-galli , Echinochloa stagnina, Echinochloa colona , and Echinochloa crus-pavonis . Amino acid sequence differences did not lead to a functional change in the sh4 gene between the shattering and non-shattering types in E. crus-galli , E. oryzicola , and E. colona . A phylogenetic analysis of the homoeologous copy sequences indicated a genomic relationship between the Asian Echinochloa species and supported that the allohexaploid E. crus-galli shares two genomes with its parental donor, E. oryzicola . The Asian perennial tetraploid species, E. stagnina , shares one genome with E. oryzicola and possesses an unknown genome. Echinochloa crus-pavonis , from the New World, shows a close affinity of two genomes with E. crus-galli and E. oryzicola . Echinochloa colona showed distant affinities in all homoeologous copies.