Effects of propylene glycol on carcass traits and its related gene expression in Korean native steers

The effects of propylene glycol (PEG) on performance, ruminal fermentation, blood glucose and insulin, carcass traits, and abundance of IGF-1 mRNA in LM and leptin mRNA in adipose tissue were examined in 20 Korean native steers, with 10 each in control and PEG-fed groups, respectively. Propylene glycol mixed with concentrate diet was provided daily at a rate of 2.5 mL/kg BW(0.75). Experimental animals were fed a concentrate diet to 1.8% of BW twice daily plus rice straw ad libitum during the 4-mo period before marketing. Daily DMI and ADG did not differ between control and PEG-fed steers. Steers receiving PEG displayed an increase (P = 0.044) in propionate concentration, whereas acetate concentration decreased (P = 0.032). Although blood glucose was not affected, serum insulin was increased (P = 0.047) by PEG feeding. Propylene glycol did not affect carcass weight, 13th-rib fat depth, marbling score, or lipid content of LM. The backfat of PEG-fed steers did not differ in leptin mRNA from control steers, whereas increased leptin mRNA was found in i.m. fat with PEG feeding. There was no treatment effect on the level of IGF-1 mRNA in the LM of the tested steers. These results indicate that the amount of PEG fed to steers was not sufficient to improve marbling score through enhanced ruminal propionate and insulin. The role of increased i.m. leptin mRNA level in PEG-fed steers remains to be further elucidated.     

Morphometric Studies on the Testis of Korean Ring-necked Pheasant (<Emphasis Type="Italic">Phasianus colchicus karpowi</Emphasis>) during the Breeding and Non-breeding Seasons

The purpose of this study was to obtain detailed quantitative information on all cell types in the testis interstitium of Korean ring-necked pheasants and to combine these data with changes in the steroidogenic function of the testis during the breeding and non-breeding seasons. For animals collected during the breeding season, their testis weights, sperm production, serum testosterone levels and leuteinizing hormone (LH)-stimulated testosterone secretion were significantly (p < 0.01) increased compared to the non-breeding season. Testes of the pheasants during the non-breeding season displayed a 98% reduction in testis volume that was associated with a decrease in the absolute volume of seminiferous tubules (98% reduction), tubular lumen (100%), interstitium (90%), blood vessels (84%), lymphatic spaces (97%), Leydig cells (79%), mesenchymal cells (51%) and myoid cells (61%) compared to the breeding season. The numbers of Leydig cells, mesenchymal cells and myoid cells per testis in the breeding season were much higher than in the non-breeding season. Although the mean volume of a Leydig cell was 74% lower in the non-breeding season, the mean volumes of myoid and mesenchymal cells remained unchanged. These results demonstrate that there are striking differences in the testicular structure of the Korean ring-necked pheasant during the breeding and non-breeding seasons. Every structural parameter of the Leydig cell was positively correlated with both testosterone serum levels and LH-stimulated testosterone secretion. The correlation of changes in hormonal status with the morphometric alterations of Leydig cells suggests that the Korean-ring necked pheasant may be used as a model to study structure-function relationships in the avian testis.     

Nano-sized Zinc in Broiler Chickens: Effects on Growth Performance,Zinc Concentration in Organs,and Intestinal Morphology

The effects of dietary supplementation of zinc (Zn) sources and concentrations were investigated on growth performance, absorption into tissues, fecal excretion, nutrient retention, and intestinal morphology in broilers fed a corn-soybean meal basal diet. A total of 525 one-day-old chicks (Ross 308) were assigned based on body weight to seven dietary treatments. There were five replicate pens for each treatment and 15 broilers per replicate pen. The dietary treatments included a basal diet (control, without supplementing Zn), and basal diet supplemented with Zn, as inorganic zinc sulfate (ZnS; 110 mg/kg); organic Zn-methionine (ZnM; 110 mg/kg); hot-melt extruded (HME) 25 zinc sulfate (27.5 mg/kg); HME50 zinc sulfate (55 mg/kg); HME75 zinc sulfate (82.5 mg/kg); or HME100 zinc sulfate (110 mg/kg) for 35 days in two phases (d 1–21, phase I and d 22–35, phase II). Bodyweight and feed efficiency of broiler chicks fed diets supplemented with increasing dietary concentrations of HME-Zn improved linearly during the study period (P<0.05). Compared to the control treatment, the ZnS, ZnM, and HME diets increased Zn concentrations in the serum and liver. Inorganic ZnS supply resulted in the highest Zn concentration in excreta. Increasing supplemented Zn content in diets as HME linearly increased Zn concentration in the excreta, serum, liver, and tibia. Broiler chicks fed diets supplemented with increasing concentrations of HME increased villus height (VH; linear and quadratic) of the jejunum and VH of the ileum (linear). Increasing concentrations of dietary Zn supplied as HME resulted in linearly enhanced dry matter, gross energy, and nitrogen retention of broilers on day 21. These results suggest that dietary HME-Zn at a lower level (55 ppm) shows the same growth performance as common ZnSO₄ at 110 ppm.     

Novel diamide resistance-linked mutation in Korean Spodoptera exigua and a LAMP assay based on a mutation-associated intronic InDel

Recently, resistance to diamide insecticides has been reported in various lepidopteran pests, including Spodoptera exigua. Six field populations and a local population were tested, and results revealed high levels of diamide resistance. We selected a diamide-resistant strain, showing LC₅₀ values 28,950- and 135,286-fold higher than those of a susceptible strain against chlorantraniliprole and flubendiamide, respectively. However, G4946E mutation in the ryanodine receptor, one of the well-known diamide resistance mechanisms, was not found in the tested resistant field populations. Instead, through genome sequencing, we found an I4790M mutation and some InDels, particularly a 29-bp insertion in the neighboring intron that was associated with this resistant allele. By using this distinct region, resistant allele diagnostic primers were designed and applied in a lamp loop-mediated isothermal amplification (LAMP) assay and general PCR. The applicable temperature of the LAMP assay was from 63 to 65 °C for 2 h with four primers. Addition of a loop primer further increased the amplification efficiency. LAMP was feasible with a broad range of DNA concentrations, with a minimum detectable concentration of 100 pg. A DNA releasing method comprising 5 min of incubation at 95 °C allowed DNA detection from some larva and adult samples. The combination of this DNA releasing technique and LAMP resulted in a rapid (up to 100 min) and accurate diagnostic strategy that could be applied to monitor and manage diamide resistance in S. exigua.

     

红喉歌鸲在韩国雪岳山国立公园大青峰地区的生境选择

自2001年5月至10月间,在韩国雪岳山国立公园大青峰地区进行了红喉歌鸲(Luscinia calliope)的生境选择研究。繁殖种群的调查结果表明,该研究地区可分成此种鸟的高、中、低3种密度分布区。红喉歌鸲多选择岳桦(Betula ermanii)和雪松(Pinus pumila)林为其栖息地,并喜欢在矮丛林和稠密灌丛中活动。表1参9。     

利用AFLP构建大白菜高密度遗传连锁图谱

以大白菜根肿病抗性材料CR Shinki DH系和感病性材料大白菜自交系94 SK杂交F2的138个单株作为构建遗传图谱的群体。利用AFLP技术通过45对引物筛选共获得835个AFLP标记,应用其中608个AFLP标记和6个与抗根肿病基因CRb紧密连锁的AFLP标记转化成的SCAR标记构建了一张包含556个标记位点、10个连锁群、覆盖基因组长度为795 cM的连锁图谱。该图谱中每个连锁群上的标记数在10~83个之间,平均图距在0.86~4.34 cM之间,连锁群长度在43.4~120.9 cM之间。CRb基因定位于第3连锁群9 cM的范围内。     

Effect of combined indole acetic acid and mepiquat chloride on endogenous gibberellins and tuber growth in Chinese yam (Dioscorea opposita Thunb.)

The combined effect of indole-3-acetic acid and mepiquat chloride on the endogenous gibberellins of aerial and underground tubers as well as tuber yield was studied on Chinese yam plant. Two plant hormones were combined in the following concentrations: IAA 50, 100, 200, and 300 ppm, plus MC 600 ppm. Combined plant hormones were foliar-sprayed once in early July. Exogenously applied IAA combining mepiquat chloride increased fresh weight of the aerial and underground tubers affecting the increase of endogenous gibberellins. The results suggest that IAA is likely to be one of the active plant hormones responsible for aerial tuber growth and enlargement, stimulating the promotion of endogenous gibberellin when combined with mepiquat chloride.     

Bisphenol-A (BPA) affects reproductive formation across generations in mice

To understand effects of Bisphenol-A (BPA) exposure on the reproductive organ across generations, we analyzed morphology of the uterus and ovary, and the methylation pattern of HOXA10 gene of the 2(nd) generation. Pregnant mice (F0) were treated with sc injection of BPA in sesame oil at various doses of 0-1,000 mg/kg Bwt on days 12-16 of gestation. Their offspring (F1) were bred by foster mice, and the offspring (F2) from F1 mice were prepared. That is, F1 mice experienced in utero BPA exposure during the developmental period of reproductive organs, while F2 mice did not at all. Using these F2 mice, the present study was carried out. Comparing to the control, the body weights in BPA exposure groups were significantly increased. Correlating with the increase of body weight, the relative weights of the ovary and uterus in each group were decreased. The histological analysis revealed expansion or emphraxis of the uterine lumen and partial loss of the uterine epithelium. Unmethylation of HOXA10 gene in the uterus was observed in the intron region. The present study suggested that BPA exposure to F0 mice could affect reproductive organ of F2 mice who were not exposed to BPA.     

Analysis of fluoroquinolone residues in edible chicken tissues using supercritical fluid extraction

We evaluated a procedure that uses high-performance liquid chromatography to determine the levels of four fluoroquinolones (ciprofloxacin, enrofloxacin, norfloxacin, and ofloxacin) remaining in chicken breast muscle, liver, and kidneys after the analytes are extracted using supercritical fluid extraction (SFE). These antimicrobial fluoroquinolones were extracted by SFE using supercritical CO2 containing 30% (v/v) methanol. The recovery, limit of detection, accuracy, and precision of this method were evaluated on the basis of fortified matrices at concentrations of 25 to 250 microg/kg. The method is validated and shown to be linear in the range of 2.5-50 microg/kg. Spike recoveries for muscle, liver and kidney samples prepared at 4 spiking levels were ranged from 56.6-104.3%, 51.2-98.4% and 62.2-97.8%, respectively. The coefficient of variation (CV) for recovery as a measure of relative variability was between 3% and 13%, and the relative standard deviation (RSD) was < 20%. The limits of quantitation (LOQ) were 10 microg/kg for enrofloxacin, 12.5 microg/kg each for ciprofloxacin and norfloxacin and 25 microg/kg for ofloxacin; these values were lower than the maximum residue levels (MRLs) authorized by the European Community. The 4 compounds were evaluated simultaneously, and the method was shown to be applicable for analyzing their residues in edible chicken tissues.     

A modeling study of soil temperature and moisture effects on population dynamics of Paronychiurus kimi (Collembola: Onychiuridae)

The effect of soil moisture on population dynamics of Paronychiurus kimi (Collembola) was examined by combining an empirical soil moisture model with a temperature-sensitive, stage-structured population model. Field observations of soil temperature were used to drive the population model, and simulations were compared to field observations of juvenile and adult densities. Simulations without soil moisture effects produced stable, interyear population dynamics and a significant correlation between simulations and observations (n=12, r ²=0.40, P<0.05) but overestimated densities during much of the year. Adding responses to soil moisture improved the fit between simulations and observations (n=13, r ²=0.40), suggesting that soil moisture is a major limiting factor on field populations of P. kimi. Moreover, an observed temporary decline in field populations during spring could be explained partly by the effects of an herbicide, paraquat (N,N′-dimethyl-gamma,gamma′-bipyridylium dichloride) (r ²=0.45), suggesting that paraquat imposes additional limits on collembolan populations.