传染性法氏囊病（Infectious bursal disease, IBD）是一种严重危害养禽业健康发展的传染病，该病的病原是传染性法氏囊病病毒（Infectious bursal disease virus, IBDV）。IBDV的基因组由双节段双股RNA组成，即A节段和B节段。传统上，依据致病性和抗原性，IBDV可分为经典株、变异株、超强毒株和弱毒株。近年来，随着IBDV的不断变异，具有新的基因特征的IBDV毒株不断出现。传统的IBDV分类方法已不能涵盖这些新出现的毒株。因此，亟需建立一种新的IBDV基因型分类方法用于IBDV的流行病学研究。近年来，A节段基因序列常被用于IBDV的基因分类。然而，对于基因组分节段的IBDV来讲，A节段和B节段在病毒的遗传演化中都很重要，仅基于A节段基因序列的基因分类方法是不全面的。而且，原有的分类方法已经不能涵盖不断出现的IBDV节段重配病毒和最新出现的IBDV新型变异株。因此，本研究率先建立了一种兼顾IBDV基因组双节段特征的新的IBDV基因分型方法。在该分型系统中，基于A节段编码的VP2高变区核苷酸序列特征，IBDV被分为9个基因群（A1、A2、A3、A4、A5、A6、A7、A8和AII）；基于B节段编码的B-maker的核苷酸序列特征，IBDV被分为5个基因群（B1、B2、B3、B4和BII）；A2又被进一步分为4个亚群（A2a、A2b、A2c和A2d）。利用新的基因分型方法，传统的经典株、变异株、超强毒株和弱毒株分别被归类于基因群A1B1、A2B1、A3B2和A8B1。本研究中鉴定的IBDV新型变异株被归类为基因群A2dB1。本研究建立的IBDV基因分型方法，是一个灵活多样的开元系统，可用于现有毒株和新出现毒株的明确鉴定，将极大地方便IBDV的分子流行病学研究。

传染性法氏囊病（Infectious bursal disease，IBD）是由传染性法氏囊病病毒（Infectious bursal disease virus，IBDV）引起的。IBD是危害养禽业的最重要的免疫抑制病之一，是影响全球养禽业可持续发展的重要限制因素。IBD在巴基斯坦也是危害养禽业的重要疫病，然而该国IBDV优势流行毒株尚不明确。本研究针对巴基斯坦主要养禽地区（旁遮普省、信德省、俾路支省和首都伊斯兰堡），开展了IBDV的流行病学研究。之前报道的巴基斯坦IBDV毒株仅显示了A节段编码的VP2基因，在GenBank上未见到过其B节段编码的VP1基因。然而，IBDV的基因组分为A、B两个节段，单独的VP2基因是无法科学地反映IBDV的真实特征的。在本研究中，运用RT-PCR技术，对覆盖29个肉鸡场的36株IBDV进行了VP1和VP2基因代表区段的扩增、测序和分析。基因遗传进化树和同源率比较研究结果显示，本研究的全部36株巴基斯坦IBDV毒株的VP2基因属于IBDV超强毒（very virulent IBDV，IBDV），而VP1基因则独立于超强毒和非超强毒之外形成了独特分支，这类毒株属于独特型节段重组IBDV毒株（vv-A/Uniq-B）。与流行于中国、印度等国家的vv-A/Uniq-B型IBDV相比，巴基斯坦IBDV毒株形成一个独立的亚群，具有明显的地域特点。本研究首次证明，具有地域特点的独特的节段重组毒株（vv-A/Uniq-B）是巴基斯坦IBDV的重要流行毒株。本研究揭示了巴基斯坦IBDV毒株的分子特征，这对于IBD疫苗的科学选择和该病的有效防控具有重要意义。

    The increase of atmospheric carbon dioxide (CO₂) concentration adversely affect several quality traits of rice grains, but the biochemical mechanism remains unclear. The objectives of this study were to determine how changes in the source-sink relationship affected rice quality. Source-sink manipulation was achieved by free-air CO₂ enrichment from tillering to maturity and partial removal of spikelet at anthesis using a japonica rice cultivar Wuyunjing 23. Enrichment with CO₂ decreased the head rice percentage and protein concentration of milled rice, but increased the grain chalkiness. In contrast, spikelet removal resulted in a dramatic increase in the head rice percentage and protein concentration, and much less grain chalkiness. Neither CO₂ enrichment nor spikelet removal affected the starch content, but the distribution of starch granule size showed distinct treatment effects. On average, spikelet removal decreased the percentage of starch granules of diameter >10 and 5–10 μm by 23.6 and 5.6%, respectively, and increased those with a diameter of 2–5 and <2 μm by 4.6 and 3.3%, respectively. In contrast, CO₂ elevation showed an opposite response: increasing the proportion of large starch granules (>5 μm) and decreasing that of <5 μm. The starch pasting properties were affected by spikelet removal much more than by CO₂ elevation. These results indicated that the protein concentration and starch granule size played a role in chalkiness formation under these experimental conditions.

Hybrid indica rice (Oryza sativa L.) cultivars play an important role in rice production system due to its heterosis, resistance to environmental stress, large panicle, and high yield potential. However, no attention has been given to its root growth dynamic responses to rising atmospheric CO2 concentration ([CO2]) in conjunction with nitrogen (N) availability. Free air CO2 enrichment (FACE) and N have significant effects on rice root growth. In this experiment, a hybrid cultivar Shanyou 63 (Oryza sativa L.) was used to study the effects of FACE and N levels on roots growth of rice. The results showed a significant increase in both adventitious root volume (ARV) and adventitious root dry weight (ARD) under the FACE treatment. The application of nitrogen also increased ARV and ARD, but the increase was smaller than that under FACE treatment. On the basis of the FACE experiment, numerical models for rice adventitious root volume and dry weight were built with the time as the driving factor. The models illustrated the dynamic development of rice adventitious root volume and dry weight after transplanting, regulated either by the influence factor of atmospheric [CO2] or by N application. The models were successfully used to predict ARV and ARD under FACE treatment in a different year with the predicted data being closely related to the actual experimental data. The model had guiding significance to growth regulation of rice root under the condition of atmospheric [CO2] rising in the future.