Additive genetic and heterotic effects in a 4 × 4 complete diallel cross‐population of Nile tilapia (Oreochromis niloticus,Linnaeus, 1758) reared in different water temperature environments in Northern Vietnam

This study aims to estimate the strain additive genetic and heterotic effects on growth and survival in a 4 × 4 complete diallel cross‐population of Nile tilapia. Mass spawning was practised in replicate hapas to simultaneously produce progeny of all crosses for performance testing in three environments (in ponds at 20–30°C, in tanks at 15–20°C and in tanks at 20–25°C). A total of 6735 individually tagged fish were tested over a grow‐out period of 278 days. Statistical analyses were carried out on 5097 body trait records available at harvest. Across the test environments, the NOVIT4 strain exhibited the highest additive genetic values for both growth and survival (19% and 33% above the pure strain mean respectively). The heterosis effect was low and not different from zero for both traits. The ranking of strains with respect to their additive genetic values generally did not change between tank environments (15–20 vs. 20–25°C). The correlations of the additive genetic performance between tank environments were also high (0.84), suggesting that strain by water temperature interaction was likely not biologically important. By contrast, the differences in both performance and survival between pond and tank environments were statistically significant, indicating that this effect should be accounted for in future breeding programmes. The large additive genetic effect among strains coupled with the non‐significant heterotic effects in our study suggest that future breeding programme in this population of Nile tilapia should be based on a wise choice of strain or by exploiting the additive genetic variation through selective breeding.     

不同因素对竹柳枝桠材重组木性能的影响

竹柳Salix discolor枝桠材的直径小,是重组木的好原材料。试验结果表明:在竹柳重组木为密度0.9 g·cm-3,脲醛树脂(UF)施胶量15%,枝桠材直径5~10 mm,木束长度150和450 mm,热压温度140℃,加压时间20 min,木束含水率6%条件下制得的竹柳重组木静曲强度为102.04 MPa,内结合强度1.99 MPa,2 h吸水厚度膨胀率3.78%,其值均达到或超过LY/T 1984-2011《重组木地板》行业标准的要求;扫描电子显微镜(SEM)图像表明:用脲醛树脂压制的竹柳重组木的管孔被压缩成椭圆形,但细胞壁本身并没有被压溃,仍然保持了其完整性,木束表面附着的胶黏剂均匀;X射线能谱(EDAX)表明枝桠材直径≥10 mm制得的重组木的碳氧比为0.55,枝桠材直径5~10 mm为0.60,枝桠材直径为≤5 mm为0.62。说明枝桠材直径对碳氧比有影响;且枝桠材制成的重组木的碳氧比高于枝桠材本身的碳氧比(0.41)。     

Epidemiological study of Kabuto Mountain virus,a novel uukuvirus,in Japan

Kabuto Mountain virus (KAMV), the new member of the genus Uukuvirus, was isolated from the tick Haemaphysalis flava in 2018 in Japan. To date, there is no information on KAMV infection in human and animals. Therefore, serological surveillance of the infection among humans and wild mammals was conducted by virus-neutralization (VN) test and indirect immunofluorescence assay (IFA). Sera of 24 humans, 59 monkeys, 171 wild boars, 233 Sika deer, 7 bears, and 27 nutria in Yamaguchi Prefecture were analyzed by VN test. The positive ratio of humans, monkeys, wild boars, and Sika deer were 20.8%, 3.4%, 33.9% and 4.7%, respectively. No positive samples were detected in bears and nutria. The correlation coefficients between VN test and IFA in human, monkey, wild boar, and Sika deer sera were 0.5745, 0.7198, 0.9967 and 0.9525, respectively. In addition, KAMV was detected in one pool of Haemaphysalis formosensis ticks in Wakayama Prefecture. These results indicated that KAMV or KAMV-like virus is circulating among many wildlife and ticks, and that this virus incidentally infects humans.     

Growth of Chaetoceros calcitrans in Sediment Extracts from Artemia franciscana Culture Ponds Points to Phosphorus Limitation

Chaetoceros calcitrans is one of the most suitable algal strains to feed Artemia because of its appropriate size, digestibility, absence of toxins, and nutritional value. Apart from light and temperature, the growth of C. calcitrans in Artemia ponds in the Mekong Delta of Vietnam depends on the supply of nutrients, especially nitrogen (N) and phosphorus (P) released from the pond bottom sediments. This study was carried out to investigate the growth of C. calcitrans in relation to the availability and proportions of N and P present in the extracts of Artemia pond bottom sediments. The results show that the sediments are depleted in dissolved reactive P (DRP) and highly unbalanced in terms of the ratio of dissolved inorganic N (DIN) to DRP. Algal density and biomass were significantly higher in the extracts with DRP concentrations above 0.1 mg P/L and DIN/DRP ratios below 100.     

In vitro primary porcine alveolar macrophage cell toxicity and African swine fever virus inactivation using five commercially supply compound disinfectants under various condition

Efficacy of African swine fever virus (ASFV) inactivation using five commercially supply compound disinfectants was evaluated under various condition. Virucidal efficacy demonstrated that products A and E could inactivate at 1:800 within 1 min for both temperatures, while products B, C and D inactivated at 1:400. However, product D could inactivate at 1:800 when the exposure time was extended to 30 min and effected only 20°C. In addition, the cytotoxicity demonstrated that products A, B, C, D and E did not significantly affect to cell at 1:51,200, 1:12,800, 1:12,800, 1:25,600 and 1:12,800 dilution, respectively. In conclusion, these disinfectants could inactivate ASFV, however, the application of these products should be performed under safety precautions to prevent cytotoxicity in humans and animals.     

A long-term observation for ecology of pathogenic Yersinia in wild rodents living in Fukushima Prefecture,Japan

From 2012 to 2021, prevalence of pathogenic Yersinia in wild rodents captured in Fukushima Prefecture, Japan was investigated twice a year to clarify the ecology of this pathogen in wild rodent populations. Pathogenic Yersinia enterocolitica O8 was isolated from 13 (1.7%) of 755 wild rodents. The Y. enterocolitica O8 isolates harbored three virulent genes (ail, fyuA, and virF). This pathogen was isolated repeatedly from wild rodents in April 2015, 2016, and 2017, in June and November 2020, and in April 2021, which was 6 of 19 times of observations. All Y. enterocolitica O8 isolates showed the same PFGE patterns. These results indicated that the same clone of pathogenic Y. enterocolitica O8 has been maintained in wild rodent populations in Fukushima Prefecture. Therefore, wild rodent populations contribute substantially to the continuous transmission of Y. enterocolitica O8 and its persistence in the ecosystem. This is the first report on the isolation of pathogenic Y. enterocolitica O8 in wild rodents in Fukushima Prefecture, Japan.     

Effect of partial harvesting strategies on Artemia biomass production in Vietnamese salt works

The effect of partial harvest strategies on the production of Artemia biomass was evaluated for 12 weeks under Vietnamese salt farm conditions. The initial stocking density was 100 nauplii L^?1. After 3 weeks of inoculation, Artemia adults were partially harvested at intervals of 1, 3, 6 and 9 days starting with an initial quantity of 30 kg ha^?1 day^?1 at first harvest, and then the quantity of harvestable biomass was adjusted according to the standing stock present in the culture pond, combined with the time needed to harvest these quantities and with the weight of biomass harvested in each pond. The results showed that in most cases, the total densities were not significantly different among harvesting frequencies (P>0.05). However, a relatively higher Artemia adult density and its standing stock were better maintained in the 3‐day than in the 1‐day interval, and were significantly higher compared with the other two harvesting frequencies. The total biomass yields were the highest (1587 kg ha^?1) in the 3‐day harvesting interval, followed by 1‐, 6‐ and 9‐day harvesting interludes, corresponding to 1323, 1091 and 975 kg ha^?1 respectively. However, no statistical difference was observed between the 1‐ and the 3‐day interval as well as between the 6‐ and the 9‐day harvest schemes (P>0.05). The results of this study suggest that partial harvest of Artemia biomass performed every 3 days appears to be an appropriate strategy to enhance biomass productivity.     

不同施肥水平对冬小麦群体动态和产量形成的影响

通过田间试验,研究不同施肥水平对冬小麦生育期群体数量、地上部养分和干物质累积、产量以及肥料利用率的影响。结果表明,氮磷钾配施在中肥以上水平可显著提高产量,但高肥与中肥相比增产不显著,说明中肥施用量较适宜,产量达6 927.1kg/hm2,比农民习惯施肥量增产13.4%,施有机肥处理可达10 443.7kg/hm2的超高产水平,比高肥增产49.1%;生育期群体数量、养分和干物质累积量大体随施肥水平提高而提高,中肥、高肥和施有机肥处理的成穗数分别为539.2、599.2和891.7万/hm2,三者间差异显著,成熟期干物质累积量则分别为15 254.1、15 600.8和26 026.2kg/hm2,施有机肥处理显著大于高肥和中肥处理;氮磷钾配施可显著提高肥料利用率,以中肥最高,N和P肥利用率分别为44.5%和24.7%,农民习惯施肥量仅为15.9%和3.7%,施有机肥处理可达71.8%和40.2%。综合来看,陕西关中地区冬小麦在只施化肥的情况下,N、P2O5、K2O适宜用量分别为180、120、75kg/hm2(目标产量7 000kg/hm2);在基施干牛粪20 000kg/hm2情况下,施N、P2O5、K2O分别为240、150、120kg/hm2,可获得超高产(目标产量10 500kg/hm2)。     

Allelochemicals of barnyardgrass‐infested soil and their activities on crops and weeds

Barnyardgrass is one of the most noxious paddy weeds in the world and causes great trouble to many crops. In a bioassay, the aqueous extract of paddy soil infested with barnyardgrass showed phytotoxic action against the growth of the tested crops and paddy weeds, of which rice was the most suppressed among the crops. In contrast, barnyardgrass was the least affected paddy weed. By the use of a separation resin, 18 compounds belonging to terpenes, derivatives of cinnamic acid and ferulic acid, long‐chain fatty acids, and steroids that were potentially involved in the phytotoxic activities in barnyardgrass‐infested soil were isolated and identified by gas chromatography–mass spectrometry analysis. Of these, the quantities of linalool, 4‐terpinenol, coumaran, methyl phenethyl ketone, and methyl ester cinnamic acid were 1.42, 0.37, 0.02, 3.12, and 4.59 μg g^?1 of the wet soil, respectively. The herbicidal activity was varied among these qualified test compounds, in which methyl phenethyl ketone and methyl ester cinnamic acid were more herbicidal than coumaran, linalool, and 4‐terpinenol. A mixture of these compounds was also the least inhibitive against the growth of barnyardgrass, but exerted strong suppression against that of rice and monochoria. The present study demonstrates that barnyardgrass possesses strong phytotoxic properties and releases plant growth inhibitors into the soil to compete with rice and other paddy weeds in its vicinity by a chemical pathway.     

废弃杨木水泥模板纤维特性及纤维板的研究

以废弃杨木水泥模板纤维为原料制造纤维板, 实现杨木的循环利用。对水泥模板以及分离好的纤维性能进行测试分析, 并分别以废弃杨木水泥模板纤维、新鲜杨木纤维为原料制造不同密度的纤维板, 讨论原料特性和施胶量对板材性能的影响。研究结果表明:废弃杨木水泥模板表面碳元素含量高于杨木单板表面, 而水泥模板表面的氧元素含量较低; 废弃杨木水泥模板纤维的堆积密度与新鲜杨木纤维基本相同; 当用水泥模板制得的纤维板密度达到0.75 g·cm-3时, 板材的力学性能和吸水厚度膨胀率(TS)值均优于其他密度的板材, 当施胶量大于等于12.0%时, 板材的弹性模量(MOE), 静曲强度(MOR), 内结合强度(IB)性能均能满足国家标准值的要求。因此, 废弃杨木水泥模板完全可以替代普通杨木制造纤维板。