Development of Thyroid Follicles and Changes in Thyroid Hormones During the Early Development of Korean Rockfish Sebastes schlegeli

The development of thyroid follicles and the change of thyroid hormone concentrations in whole body were examined, and the relationship between thyroid follicle differentiation and growth were also studied during early development of Korean rockfish Sebastes schlegeli . Total length (TL) and body weight (BW) of larva at parturition were 6.3 ± 0.1 mm and 3.6 ± 0.1 mg respectively. The larvae transformed to juveniles from 20 to 30 d after parturition with continuous growth. The thyroid primordium of the rockfish was observed histologically in newly born larvae, suggesting that the thyroid primordium may have been formed during yolk-sac larval stage after hatching as with other marine telosts. In addition, although the Korean rockfish is a viviparous fish, the developmental features of the thyroid gland in number, size and shape are very similar to the general development features of marine oviparous fish. As the larvae grew, the thyroid follicles of Korean rockfish increased in number, became variable in size, and changed from the normal spheroid/ovoid shape to more irregular forms in shape after parturition, and then concentrated mostly along the areas immediately adjacent to the ventral aorta. In addition, thyroid cell height and thyroid hormone concentrations were related with physiological activity at a specific developmental stage.     

The effects of medetomidine on cardiac function in normal cats measured by radionuclide ventriculography

To assess the effects of medetomidine, an α₂-adrenoceptor agonist, on cardiac function, radionuclide ventriculograms (RNV) were performed in 7 normal anesthetised cats before and after im administration of the drug. Ejection fraction (EF), peak ventricular ejection rate (PVER), peak ventricular filling rate (PVFR), time to peak ejection (TPE) and time to peak filling (TPF) were determined. Medetomidine caused significant reductions in EF (baseline 55.0 ± 10.8%, post medetomidine 43.3 ± 10.7%), PVER (baseline 4.38 ± 0.83 EDV/s, post medetomidine 3.28 ± 0.73 EDV/s) and PVFR (baseline 4.46 ± 1.42 EDV/s, post medetomidine 3.05 ± 1.27 EDV/s). There was also a significant decrease in heart rate following medetomidine administration (baseline 115 ± 27.2 bpm, post medetomidine 100 ± 21.2 bpm). The TPE and TPF did not change significantly following medetomidine. The observed decrease in cardiac function may have been caused by a drug-induced increase in systemic vascular resistance, and the bradycardia due to central nervous system depression.     

Experimental in utero inoculation of late-term swine fetuses with porcine circovirus type 2.

All 37 fetuses of 3 laparotomized pregnant sows at 86, 92, and 93 days of gestation were inoculated intramuscularly through the uterine wall with porcine circovirus type 2 (PCV-2). The sows were allowed to farrow, and blood and tissue samples were collected from their piglets before and after suckling colostrum. Thirteen fetuses from 2 sows at 90 and 103 days of gestation were used as controls. Of the 37 PCV-2 inoculated fetuses, 24 were grossly normal and 13 were mummified, stillborn, or weak-born at farrowing. Infection with PCV-2 was demonstrated in various tissues of grossly normal and abnormal fetuses by virus isolation, polymerase chain reaction, and immunohistochemical methods. Antibodies specific to PCV-2 were also detected from the sera or thoracic fluids of abnormal fetuses and unsuckled normal pigs. No evidence of PCV-2 infection was found in any control fetuses. The present results confirm previous findings that PCV-2 can infect late-term swine fetuses and may cause reproductive abnormalities.     

QUANTITATIVE99mTc-PERTECHNETATE THYROID SCINTIGRAPHY IN NORMAL BEAGLES

This study was done to investigate the validity of published canine thyroid/salivary (TS) rations of approximately i in normal dogs and to detemine thyroid uptak of ^99mTc-pertechnetate (pertechnetate) measured as percent uptake of injected dose. These parameters were evaluated in 13 Beagle dogs over a 4 hour period. Mean ± standard deviation (SD) and median T/S ratios of 1.2 ± 0.3 and 1.1 were essentially the same at twenty minutes and 1 hour. T/S Values ranged from 0.9 to 2.2 at 20minutes and from 0.8 to 2.4 at 1 hour. T/S ratio values progressively declined over the subsequent time intervals with mean ± SD and median values of 0.6 ± 0.2 and 0.6, respectively, measured at 4 hour. The mean with a rang of 0.28% to 0.90%. The mean ± SD time interval from injection of pertechanetate to maximum uptake within the thyroid gland was 160 ± 55 minutes with a range 31–240 minutes. The data derived from this study of normal dogs may be useful in the evaluation of dogs with thyroidal diseases including hypthyroidism     

Genetic variation in a Panicum coloratum L. population with a limited germplasm base

Summary The U.S. kleingrass (Panicum coloratum L.) germplasm collection is relatively small, and genetic variation for many agronomic traits has not been determined. This study was conducted to explore variability and predict expected progress from selection for several morphological characters related to forage production and establishment in a narrow-based population of kleingrass. Heritabilities and genetic gain were calculated from the analysis of half-sib families in a 2-yr study. Narrow-sense heritabilities were low to moderate and predicted small gains for most characters. Leaf width, however, was consistently heritable in both years, and gains in width of 12.5% per year could be achieved with family selection. Leaf width was also significantly correlated with leaf mass and culm mass. Thus, increases in leaf and culm dry mass accumulation can be achieved by direct selection for leaf width. Two seedling root growth parameters were also heritable, indicating that genetic gain could be achieved for seedling establishment in this population. Heritabilities for number of adventitious roots and length of longest adventitious root at 14 days after emergence were much higher in the second year of the study. This was attributed to the larger number of plants sampled in the second year.     

DNA markers for eating quality of indica rice in Indonesia

Rice eating quality is considered to be one of the top priorities in determining the agronomical value of rice; thus, the rapid evaluation of eating quality at early breeding generations in breeding programmes for better eating quality is of great importance. In an attempt to develop DNA markers associated with eating quality of indica rice, we used multiple regression analysis to test 54 markers, which were preselected for their possible association with eating quality, using 24 indica varieties with different palatability scores. Of these markers, eighteen markers were found to be significantly associated with palatability according to sensory evaluation. Accordingly, a marker set in the model regression equation with a high R² (0.997) was formulated to estimate indica rice palatability. Validation suggests that markers and the statistical parameters formulated by the equation could be a potential tool to predict the palatability of cooked Indonesian indica rice and could be reliable in developing country‐dependent model equations for eating quality.     

Improved drought tolerance of transgenic Zea mays plants that express the glutamate dehydrogenase gene (gdhA) of E. coli

Genetic modification of nitrogen metabolism via bacterial NADPH- dependent glutamate dehydrogenase (GDH; E.C.4.1.2.1) favorably alters growth and metabolism of C3 plants. The aim of this study was to examine the effect of expression of GDH in the cytoplasmic compartment of Zea mays cells. The gdhA gene from Escherichia coli , that encoded a NADPH-GDH, was ligated to the ubiquitin promoter that incorporated the first intron enhancer and used to transform Z. mays cv. ‘H99’ embryo cultures by biolistics. R0–R3 generations included selfed inbreds, back-crossed inbreds, and hybrids with B73 derivatives. The lines with the highest GDH specific activity produced infertile R0 plants. The highest specific activity of GDH from the fertile Z. mays plants was sufficient to alter phenotypes. Plant damage caused by the phosphinothricin in gluphosinate-type herbicides, glutamine synthetase (GS; EC 6.1.3.2) inhibitors, was less pronounced in Z. mays plants with gdhA pat than in gusA pat plants. Germination and grain biomass production were increased in gdhA transgenic plants in the field during seasons with significant water deficits but not over all locations. Water deficit tolerance under controlled conditions was increased. Crops modified with gdhA may have value in semi-arid locations.     

Breeding system, genetic diversity and clonal structure in the sub-alpine forb Rutidosis leiolepis F. Muell. (Asteraceae)

Genetic markers, controlled pollinations and chromosome analysis were used to examine the breeding system, clonal structure, genetic diversity and cytological complexity of populations of the endangered sub-alpine forb Rutidosis leiolepis. Results show that R. leiolepis: (1) has a strong sporophytic self-incompatibility system; (2) exhibits significant clonality and that the importance of vegetative reproduction increases at higher altitudes; (3) is genetically diverse, but that variation within populations decreases and differentiation among populations increases with altitude; and (4) is diploid with 2n=22 throughout its geographic range. Based on these results, low altitude populations around Cooma and Happy Valley should be made priority areas for in situ conservation in the Species Recovery Plan currently being developed by the New South Wales National Parks and Wildlife Service because they exhibit the most sexual reproduction and highest levels of genetic variation within the species. They may also be demographically more viable in the long term, having larger effective population sizes and less likelihood of mate limitation due to low S allele richness than high altitude populations. Sampling strategies for ex situ conservation should vary from large collections within populations at low altitudes to smaller collections spread across populations at higher altitudes where more of the genetic diversity is partitioned among sites. This should give maximum representation of the species' gene pool for minimum sampling effort.     

A study of airborne metals in Calcasieu Parish,Louisiana using the lichens,Parmelia praesorediosa and Ramalina stenospora

Two common species of lichens from southwestern Louisiana, Parmelia praesorediosa and Ramalina stenospora, were analyzed thrice over a period of 9 mo. Samples were analyzed for Th, Cs, Se, Hg, Cr, Ir, Ce, Sc, Rb, Fe, Zn, Co, Ta, Eu, K, and Sb. No statistical differences in concentration over the time interval studied were seen. However, discriminant analysis showed a significant (>90%) difference between elemental content and species. The data could be separated into two geographical areas that were statistically different. Highest concentrations were observed within a 10.8-km radius of the industrial/urban zone.