黑石顶自然保护我南亚热带常绿阔叶林的凋落物

分析了黑石顶自然保护区南亚热带常绿阔叶林凋落物的季节变化及１８种常见种的落叶规律。结果表明凋落物有明显的季节变化,４ａ平均凋落量为４．６３０ｔ．ｈｍ＾－２;．ａ＾－１。     

小良热带人工混交林的凋落物及其生态效益研究

对小良热带人工混交林１０年凋落量及其季节和年际动态研究表明,小凋落物总量年均５．５３９ｔ·ｈｍ－２;凋落量的季节变化明显,一般以湿季的７月为凋落高峰;随着人工林的发育,其凋落物量的年际变化逐渐稳定;森林枯枝落叶层贮量为４．９ｔ·ｈｍ－２,少于其年均凋落量,处于分解大于积聚的周转过程中;森林枯枝落叶层的存在可降低温度,提高湿度,显著减少径流量和泥沙流失量,并可提高土壤肥力和增加土壤动物的多样性．     

广东黑石顶自然保护区南亚热带常绿阔叶林凋落物能流的研究

分析了广东处黑石顶自然保护区南亚热带常绿阔叶林凋落物流的年际变化和季节变化。结果表明凋落物有明显的年限和季节变化。４年间平均凋落物流为９．３６３ＭＪ．ｍ＾－２．ａ＾－１,其中凋落叶占８１．９５％,１９９４年凋落物能流为７．３５７ＭＪ．ｍ＾－２．ｓ＾－１,低于平均值２１．４％。说明了影响我国常地林凋落物形成的主要环境因素是水分条件的年限和季节变化。     

武夷山甜槠林细根生物量和生长量研究

对武夷山甜槠林细根生物量和生长量的季节动态及其在不同群落发育阶段下的变化进行了初步研究,并对细根在养分归还中的作用进行了分析．结果表明,甜槠成熟林细根生物量为１０．６４５ｔ·ｈｍ－２,生长量为７．３７１５ｔ·ｈｍ－２·ａ－１,分解量为４．６７７５ｔ·ｈｍ－２·ａ－１,年周转率０．６９次;细根生物量和生长量随林龄增长的变化模式为单峰型曲线,生物量至３４龄时达到最大值,生长量至群落郁闭阶段（５８龄）达到最大值;甜槠成熟林中,通过细根死亡的Ｎ素归还量占群落年归还总量的４９．５％,多于凋落物途径,Ｐ、Ｍｇ归还量所占比例为４２．３％和２８．９％,略低于凋落物途径;Ｋ、Ｃａ归还以降水淋溶为主,其次是凋落物途径,而细根途径仅占总归还量的１９．３％和９．２％．     

西藏林芝云杉林凋落物的特征研究

本文报道了西藏林芝云杉林的凋落量、凋落特征及凋落物中主要营养元素（Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ）的含量。３年的测定结果表明,林芝云杉林的年均凋落量为３８４３．２３ｋｇｈｍ－２ａ－１,其中枯叶量占７０．５２％,枯枝、杂物各占１４．３３％和１５．１４％。凋落物中主要营养元素的含量为１００．６５ｋｇｈｍ－２ａ－１。凋落物均有明显的季节变化规律。各类凋落物的凋落特征从一定角度反映了林芝云杉林群落一般的生物学与生态学特性以及对西藏高原环境条件的适应性。     

羊草草原分解者亚系统的特性及作用

在内蒙古羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ）草原,对其分解者亚系统的特性及作用开展研究,采用网袋法对不同物候期羊草植株和凋落物的分解作用进行了测定。结果如下：１．植株分解的最初２－３ａ中,其残体表面的微生物生物量及转化酶、蛋白酶的活性均呈现返青期植株＞结实期植株＞果后营养期植株＞凋落物。植株分解的速度亦为上述规律。２．羊草植株被分解后,可提高临近土壤的微生物活性。各植株分解均引起土壤的Ｃ／Ｎ值下降,老熟植株分解使土壤的ＨＡ／ＦＡ值升高。３．幼嫩植株分解时,其体内营养元素会较快释放;凋落物分解则导致氮和磷元素的积累,但钾不会。４．通过指数衰减模型估算,羊草凋落物的分解常数为０．１５３ｇ／ｇ·ａ,９５％被分解掉约需１９ａ时间。５．羊草草原凋落物的最大积累量为年输入量的６．５４倍,即１１７５．６ｇ／ｍ￣２。６．分用凋落物的微生物其生物量平均为４．４×１０￣（－３）ｇ／ｇ·ＤＷ,微生物所含能量仅占凋落物贮存能量的０．５％左右。     

福建和溪亚热带雨林凋落物营养元素动态

探讨了福建和溪亚热带雨林主要营养元素通过凋落物的归还动态．结果表明,该森林一年中凋落物不同组分各元素的含量具有波动性,加权平均含量为Ｎ＞Ｋ＞Ｃａ＞Ｍｇ＞Ｐ（落果Ｃａ＝Ｍｇ、落枝Ｃａ＞Ｋ）。通过凋落物归还Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ元素的年库流量,分别为８７．４１、３．８２、４０．８０、２８．８１和１５．３２ｋｇｈｍ（－２）,灰分量为２８４．５７ｋｇｈｍ（－２）,其中以落叶形式居最大,分别各占总量的７３．４％、６８．１％、．７７．２％、７２．９％、７４．５％和７９．９％;各元素的年库流量与年凋落物量的月分布相一致,有明显的季节性．森林地表残留物Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ元素的累积储量．分别为５４．８３、２．４５、９．６９、１７．０和９．２５ｋｇｈｍ（－２）．五种元素在林下地表的滞留时间,分别为Ｎ０．６１、Ｐ０．６１、Ｋ０．２３、Ｃａ０．５６和Ｍｇ０．５３年．     

内蒙古锡林河流域大针茅草原土壤呼吸和凋落物分解的CO2排放速率研究

根据静态气室法对大针茅（ＳｔｉｐａｇｒａｎｄｉｓＳｍｉｒｎ）草原整个生长季土壤呼吸和地表凋落物分解释放ＣＯ２量的测定结果,分析了大针茅草原土壤呼吸和凋落物分解速率的季节动态,并探讨了其与地上、地下生物量及环境因子的关系。结果表明：（１）在整个观测期内,大针茅草原由土壤呼吸和地表凋落物分解所释放ＣＯ２速率的季节动态呈梯形曲线,８月下旬达到最大值２．５１ｇＣ·ｍ－２·ｄ－１;（２）ＣＯ２排放速率的季节变化趋势与地上生物量,尤其是地上绿色生物量部分的季节动态有一定同步性,而与地下生物量的季节变化趋势不同步,甚至相反;（３）地表凋落物层有减缓土壤向大气排放ＣＯ２的作用;（４）土壤呼吸和地表凋落物分解释放ＣＯ２的速率（ｙ）与土壤湿度（ｘ）显著相关,其对数回归模型为：ｙ＝３．４６９ｌｏｇ１０ｘ－２．０５３（ｒ＝０．９２,Ｐ＜０．０１）。     

草原土壤N2O释放及全球变暖影响下土壤养分变化的反馈效应

对草原土壤Ｎ２Ｏ释放及其受全球变暖土壤养分变化的影响研究表明,以沼泽泥炭土Ｎ２Ｏ释放量最大,生长季节为１３～１２．２ｋｇＮ·ｈｍ－２·ａ－１,其次灰壤土,为１．５～２．４ｋｇＮ·ｈｍ－２·ａ－１,酸性棕壤最小,为０～３．２ｋｇＮ·ｈｍ－２·ａ－１;Ｎ２Ｏ的释放层灰壤土在０～５ｃｍ,其它２种土壤为０～１０ｃｍ;施肥试验表明,Ｎ、Ｐ肥在生长季节对土壤Ｎ２Ｏ释放量影响不显著,但在生长季末期,Ｎ肥对酸性棕壤及灰壤土Ｎ２Ｏ影响显著,施肥后第３天酸性棕壤由对照的１．３提高到４４．２ｋｇＮ·ｈｍ－２·ａ－１,灰壤土则由对照的１．９提高到３１．１ｋｇＮ·ｈｍ－２·ａ－１,说明全球变暖对土壤有机质分解的影响不会诱发Ｎ２Ｏ释放量的大幅度增加．     

西双版纳季节雨林与橡胶多层林凋落物动态的比较研究

本语文对西双版纳季节雨林及橡胶多层林的凋落物量动态、各组分的季节变化规律、林地残留物现存量及其分解进行了研究,分析比较了两个种群落的凋落节律,结果显示,“双凋落峰”及“叶分解速率较枝分解更快”为两类群落的共有特征;森林凋落物量及凋落物分解速率则因群落类型而异,橡胶多层林年凋落物总量为９．８５±０．７８ｔ·ｈｍ＾－２·ａ＾－１,大于季节雨林的年凋落物总量８．４２±０．１６ｔ·ｈｍ＾－２·ａ＾－１。     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV     

Mink Circovirus Can Infect Minks,Foxes and Raccoon Dogs

正Dear Editor,Mink circovirus (MiCV), which is clustered in the genus Circovirus of the family Circoviridae, was first described in minks from farms in Dalian, China in 2013 (Lian et al.2014). The complete single-stranded circular genome of the virus is 1,753 nucleotides long and contains two major open reading frames (ORFs), designated ORF1 (Rep gene)and ORF2 (Cap gene)(Lian et al. 2014; Ge et al. 2018).Sequence analysis has shown that MiCV is most closely     

CypA Regulates AIP4-Mediated M1 Ubiquitination of Influenza A Virus

Cyclophilin A (CypA) is a peptidyl-prolyl cis/trans isomerase that interacts with the matrix protein (M1) of influenza A virus (IAV) and restricts virus replication by regulating the ubiquitin–proteasome-mediated degradation of M1. However,the mechanism by which CypA regulates M1 ubiquitination remains unknown. In this study, we reported that E3 ubiquitin ligase AIP4 promoted K48-linked ubiquitination of M1 at K102 and K104, and accelerated ubiquitin–proteasome-mediated degradation of M1. The recombinant IAV with mutant M1 (K102 R/K104 R) could not be rescued, suggesting that the ubiquitination of M1 at K102/K104 was essential for IAV replication. Furthermore, CypA inhibited AIP4-mediated M1 ubiquitination by impairing the interaction between AIP4 and M1. More importantly, both the mutations of M1 (K102 R/K104 R) and CypA inhibited the nuclear export of M1, indicating that CypA regulates the cellular localization of M1 via inhibition of AIP4-mediated M1 ubiquitination at K102 and K104, which results in the reduced replication of IAV.Collectively, our findings reveal a novel ubiquitination-based mechanism by which CypA regulates the replication of IAV.