Empirical Growth Curve Estimation Using Sigmoid Sub-functions that Adjust Seasonal Compensatory Growth for Male Body Weight of Thoroughbred Horses

Thoroughbred horses are seasonal mating animals, raised in northern regions or countries. Foals born yearly in spring generally show a typical seasonal compensatory growth pattern, in which their growth rate declines in the first winter and increases in the next spring. In this study, a new empirical adjustment approach is proposed to adjust for this compensatory growth when growth curve equations are estimated, by using 1,633 male body weights of Thoroughbreds as an illustrating example. Based on general Richards growth curve equation, a new growth curve equation was developed and fit to the weight-age data. The new growth curve equation had a sigmoid sub-function that can adjust the compensatory growth, combined with the Richards biological parameter responsible for the maturity of animals. The unknown parameters included in the equations were estimated by SAS NLMIXED procedure. The goodness of fit was examined by using Akaike’s Information Criterion (AIC). The AIC values decreased from 13,053 (general Richards equation) to 12,794 (the newly developed equation), indicating the better fit of the new equation to the weight-age data. The shape of the growth curve was improved during the period of compensatory growth. The proposed method is one of the useful approaches for adjusting seasonal compensatory growth in growth curve estimations for Thoroughbreds, and for their management during the compensatory period. Based on this approach, the optimal growth curve equations can be estimated also for female body weight of Thoroughbreds or other growth traits affected by seasonal compensatory growth.     

中国云南省滇池盆地东南区由于土地利用方式的变化（从水田变为旱地或温室土壤）导致土壤理化性质的变化研究

Paddy fields in the southeastern basin of Dianchi Lake have rapidly changed to greenhouses since 1999. A total of 61 surface soil samples, including 43 greenhouse soils, 12 upland soils, and 6 paddy soils, were collected from a flat lowland area mainly used for agricultural production fields in the southeastern basin of Dianchi Lake. Analyses of the soil samples indicated that the greenhouse soils were characterized by a lower organic matter content, lower pH, and higher soluble nutrients than the paddy soils in the area. The lower organic matter content of the greenhouse soils was ascribed to environmental or management factors rather than the clay content of the soil. Accumulation of soluble nutrients, especially inorganic N, was due to over-application of fertilizers, which also caused soil acidification. The average amount of readily available N, P, and K accumulated in the greenhouse soils was estimated to be equal to or higher than the annual input of these nutrients as a fertilizer, indicating that a reduction in fertilizer application was possible and recommended. In contrast, a very low available Si content was observed in the paddy soils, suggesting the need for Si application for rice production.     

KISS1 Gene Expression in the Developing Brain of Female Pigs in Pre- and Peripubertal Periods

Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents, ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1 gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4% paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs.     

Apparent digestibilities of diets based on timothy and Italian ryegrass hay harvested in different regions in Japan fed to exercising Thoroughbreds

The apparent digestibility of diets based on timothy hay harvested in Hidaka in Hokkaido (HT) and Italian ryegrass hay harvested in Miyazaki in Kyushu (MI) were compared in Thoroughbreds undergoing exercise. The nitrogen retention and plasma‐free amino acid (AA) concentrations were also examined to evaluate the quality of the protein contained in the two types of hay. Four male Thoroughbreds (aged 34.4 ± 0.9 months (mean ± standard deviation) and weighing 506.3 ± 30.4 kg) undergoing exercise training at 80% of maximal heart rate were used for the study, and the apparent digestibility of the diets based on HT and MI was assessed. The net nitrogen balance was also measured by subtracting the amount of nitrogen excreted in the feces and urine from the total nitrogen intake. The apparent digestibilities of dry matter, energy, neutral detergent fiber and ether extract were all higher in the MI group than in the HT group (P < 0.05). The larger energy digestibility in the MI group (56.8 ± 3.3%) compared with that in the HT group (51.6 ± 2.4%) was attributed to the relatively easy digestibility of hemicellulose. The net nitrogen balance and plasma AA concentrations did not differ significantly between the two forage groups. We concluded that the nutritive value of MI is adequate for exercising horses, even though the timothy and Italian ryegrass used in this study were second cuttings, and their nutrient values were not easily comparable.     

Expression of <Emphasis Type="Italic">Xanthomonas oryzae </Emphasis>pv. <Emphasis Type="Italic">oryzae hrp</Emphasis> Genes in XOM2, a Novel Synthetic Medium

To analyze the regulation of hrp expression and to detect and identify hrp-dependent secretion proteins of plant-pathogenic bacteria, an appropriate hrp-inducing medium is indispensable. In this study, two efficient hrp-inducing media for Xanthomonas oryzae pv. oryzae were designed by assaying the expression of a hrcU (the first gene of the hrpC operon) and a gus (β-glucuronidase) fusion gene. We modified XVM2, which is a hrp-inducing medium for X. campestris pv. vesicatoria, by adding 0.01% xylose in place of fructose and sucrose (0.18 and 0.34%, respectively) as a sugar source. The resulting medium induced approximately 15-fold more GUS activity from transformants containing a hrcU::gus gene than did XVM2. Moreover, a methionine-containing synthetic medium with 0.18% xylose as a sugar source was able to induce much stronger expression of HrcU::GUS, with GUS activity approximately 100-fold greater than that in XVM2. Induction depended on a regulator, HrpXo, and the PIP (plant-inducible-promoter) box, suggesting that HrcU::GUS was expressed in a hrp-dependent manner. The induction of operons hrpA to hrpF in XOM2 was also confirmed. These results suggest that both media, especially XOM2, are highly efficient hrp-inducing media for X. oryzae pv. oryzae. Received 7 October 2002/ Accepted in revised form 22 November 2002     

Identification of an antihypertensive peptide derived from chicken bone extract

A novel angiotensin‐converting enzyme (ACE) inhibitory peptide was isolated and purified from chicken bone extract by enzymatic digestion. The peptide was defined as an ACE inhibitor, and it demonstrated antihypertensive activity following oral administration to spontaneously hypertensive rats (SHRs). The results of this study suggest that peptides derived from an extract of chicken bones, administered orally, have the ability to reduce the blood pressure of SHRs significantly over a short period of time (3 h). Moreover, the blood pressure then remains low for 3 h. This peptide derived from chicken bones may therefore have great value as a short‐term remedy for chronic conditions such as high blood pressure. The amino acid sequence of the peptide was YYRA (Tyr‐Tyr‐Arg‐Ala), which was the origin of the Ig heavy chain V region (27–30 position). The IC₅₀ value of its synthetic peptide was 33.9 μg/mL. We suggest that the ACE inhibitory and antihypertensive peptides derived from chicken bone extract may contribute to develop physiologically functional foods or improve food functionality.