Molecular Characterization of Southern Rice Blacked‐Streaked Dwarf Virus (SRBSDV) from Vietnam

Southern rice black‐streaked dwarf virus (SRBSDV) is a novel putative member of the genus Fijivirus, family Reoviridae. We report here the genomic sequences of a Vietnamese isolate (SRBSDV‐V). The total genome of SRBSDV‐V has 29 115 nucleotides (nt), nine nt shorter than SRBSDV‐GD or ‐HN, but similar in organization to these two Chinese isolates. Nucleotide diversities among SRBSDV isolates were much lower than those among the corresponding ORFs of the available RBSDV isolates and there was a lower purifying selection pressure on SRBSDV than RBSDV, providing first molecular evidence for the view that SRBSDV is of recent origin. In studies of all available SRBSDV sequences, there was no obvious correlation between geographic distances and phylogenetic distribution. A high frequency of genetic recombination was found among both Chinese and Vietnam SRBSDV isolates, suggesting that recombination may play an important role in the molecular variation and evolution of SRBSDV.     

小麦-大麦矮秆易位系T2DL·2HS的鉴定

利用形态学、细胞学及分子标记技术对从普通小麦和农家二棱大麦的杂交后代中选育的矮秆种质系WB7-3进行了鉴定。结果表明:WB7-3田间农艺性状较好,且表现为矮秆;根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MⅠ)染色体构型为2n=21Ⅱ,基因组原位杂交(GISH)未出现杂交信号;位于大麦2H染色体短臂上的特异STS引物ABC454能在WB7-3中扩增出大麦特征条带,表明WB7-3含有大麦2HS的染色体片段;利用210对位于小麦各条染色体上的SSR引物对其进行扩增结果显示,2DS上4对引物(Xgdm35、Xgdm5、Xgwm261和Xgwm455)在WB7-3中有条带缺失,由此确定该小大麦矮秆材料WB7-3是一个2DL/2HS小片段易位系。     

Estimates of Lost Material Stock of Buildings and Roads Due to the Great East Japan Earthquake and Tsunami

This article describes research conducted for the Japanese government in the wake of the magnitude 9.0 earthquake and tsunami that struck eastern Japan on March 11, 2011. In this study, material stock analysis (MSA) is used to examine the losses of building and infrastructure materials after this disaster. Estimates of the magnitude of material stock that has lost its social function as a result of a disaster can indicate the quantities required for reconstruction, help garner a better understanding of the volumes of waste flows generated by that disaster, and also help in the course of policy deliberations in the recovery of disaster‐stricken areas. Calculations of the lost building and road materials in the five prefectures most affected were undertaken. Analysis in this study is based on the use of geographical information systems (GIS) databases and statistics; it aims to (1) describe in spatial terms what construction materials were lost, (2) estimate the amount of infrastructure material needed to rehabilitate disaster areas, and (3) indicate the amount of lost material stock that should be taken into consideration during government policy deliberations. Our analysis concludes that the material stock losses of buildings and road infrastructure are 31.8  and 2.1 million tonnes, respectively. This research approach and the use of spatial MSA can be useful for urban planners and may also convey more appropriate information about disposal based on the work of municipalities in disaster‐afflicted areas.     

Global reductions in seafloor biomass in response to climate change

Seafloor organisms are vital for healthy marine ecosystems, contributing to elemental cycling, benthic remineralization, and ultimately sequestration of carbon. Deep‐sea life is primarily reliant on the export flux of particulate organic carbon from the surface ocean for food, but most ocean biogeochemistry models predict global decreases in export flux resulting from 21st century anthropogenically induced warming. Here we show that decadal‐to‐century scale changes in carbon export associated with climate change lead to an estimated 5.2% decrease in future (2091–2100) global open ocean benthic biomass under RCP8.5 (reduction of 5.2 Mt C) compared with contemporary conditions (2006–2015). Our projections use multi‐model mean export flux estimates from eight fully coupled earth system models, which contributed to the Coupled Model Intercomparison Project Phase 5, that have been forced by high and low representative concentration pathways (RCP8.5 and 4.5, respectively). These export flux estimates are used in conjunction with published empirical relationships to predict changes in benthic biomass. The polar oceans and some upwelling areas may experience increases in benthic biomass, but most other regions show decreases, with up to 38% reductions in parts of the northeast Atlantic. Our analysis projects a future ocean with smaller sized infaunal benthos, potentially reducing energy transfer rates though benthic multicellular food webs. More than 80% of potential deep‐water biodiversity hotspots known around the world, including canyons, seamounts, and cold‐water coral reefs, are projected to experience negative changes in biomass. These major reductions in biomass may lead to widespread change in benthic ecosystems and the functions and services they provide.     

Do grasslands act as a perpetual sink for carbon?

It is increasingly commonly suggested that grasslands are a perpetual sink for carbon, and that just maintaining grasslands will yield a net carbon sink. I examine the evidence for this from repeated soil surveys, long term grassland experiments and simple mass balance calculations. I conclude that it is untenable that grasslands act as a perpetual carbon sink, and the most likely explanation for observed grassland carbon sinks over short periods is legacy effects of land use and land management prior to the beginning of flux measurement periods. Simply having grassland does not result is a carbon sink, but judicious management or previously poorly managed grasslands can increase the sink capacity. Given that grasslands are a large store of carbon, and that it is easier and faster for soils to lose carbon that it is for them to gain carbon, it is an important management target to maintain these stocks.     

Grass allometry and estimation of above‐ground biomass in tropical alpine tussock grasslands

The puna/páramo grasslands span across the highest altitudes of the tropical Andes, and their ecosystem dynamics are still poorly understood. In this study we examined the above‐ground biomass and developed species specific and multispecies power‐law allometric equations for four tussock grass species in Peruvian high altitude grasslands, considering maximum height (h_max), elliptical crown area and elliptical basal area. Although these predictors are commonly used among allometric literature, they have not previously been used for estimating puna grassland biomass. Total above‐ground biomass was estimated to be of 6.7 ± 0.2 Mg ha^?1 (3.35 ± 0.1 Mg C ha^?1). All allometric relationships fitted to similar power‐law models, with basal area and crown area as the most influential predictors, although the fit improved when tussock maximum height was included in the model. Multispecies allometries gave better fits than the other species‐specific equations, but the best equation should be used depending on the species composition of the target grassland. These allometric equations provide an useful approach for measuring above‐ground biomass and productivity in high‐altitude Andean grasslands, where destructive sampling can be challenging and difficult because of the remoteness of the area. These equations can be also applicable for establishing above‐ground reference levels before the adoption of carbon compensation mechanisms or grassland management policies, as well as for measuring the impact of land use changes in Andean ecosystems.     

水稻半矮化多分蘖突变体f2-132的表型分析和基因定位

半矮化多分蘖突变体f2-132由60Co-γ辐射诱变粳稻品种F2-285A获得。遗传分析表明该性状受1对隐性基因控制,已将突变基因定位在第4染色体长臂上2个Indel标记C4-Z3和C4-Z4之间,物理距离为46 kb。该区间内包含一个已报道的多分蘖基因D17/HTD1,对f2-132中的D17基因测序发现编码区第395位的碱基由T突变为C,导致第132位的氨基酸由苯丙氨酸变成丝氨酸。D17/HTD1编码类胡萝卜素裂解双加氧酶7(CCD7,carotenoid cleavage dioxygenase 7),是植物激素独脚金内酯(SLs,strigolactones)合成途径中的重要酶之一。利用SLs的人工合成类似物GR24处理f2-132,其多分蘖表型受到抑制。     

Feedback regulation of constant leaf standing crop in Sasa tsuboiana grasslands

The standing crop of current leaves of Sasa tsuboiana was measured on the upper slopes of Mount Horai, Shiga prefecture, central Japan. Upper one-year-old branches in the canopy produced greater mass of current leaves than lower ones. Furthermore, culms in artificially thinned plots produced larger leaf mass per culm than those in control plots. These results reveal that leaf production is positively correlated with light intensity. Therefore, when the leaf standing crop in a given year is somewhat smaller than usual, it may increase in the following year because the branches will receive stronger light. This feedback regulation causes uniformity in the horizontal distribution of the leaf standing crop. The constancy of the leaf standing crop throughout dense stands of different heights indicates that a common equilibrium value of the leaf standing crop exists. This uniform distribution leads to an almost-uniform weak light intensity under the canopy of S. tsuboiana, and can consequently exclude other plant species.     

浙江和河北发生的一种水稻、小麦、玉米矮缩病是水稻黑条矮缩病毒引起的

以浙江省的水稻黑条矮缩病和河北省的玉米粗缩病的病毒分离物为材料,对我国南北方两种病毒分离物进行了比较研究。两种病毒分离物的粒子大小形态相似,且在血清学上密切相关;二者的介体、寄主相同,并引起相同的症状,提纯两种病毒分离物的基因组片段凝胶电泳显示它们相应的基因组片段之间大小极相似。根据水稻黑条矮缩病毒（Rice black strecaked dwarf virus),RBSDV的S7和S8设计引物,利用PR－PCR技术,在两种病毒分离物中均可特异扩增到预期大小的片段,序列测定比较分析表明：它们的同源性达97．0％－98．9％,与日本RBSDV的同源性（92．2％－95．5％）高于与意大利MRDV的同源性（76．6％－88．4％）。从而认为我国南方的水稻黑条矮缩病和北方和玉米粗缩病都是同一种病毒－RBSDV引起的,也就是说我国北方的玉米粗缩病病原实际上是水稻黑条矮缩病毒,而不玉米粗缩病毒。     

Recovery plan for an exploited species, southern bluefin tuna

Southern bluefin tuna (SBT) were heavily depleted in the mid-1980s, and the fishing quota has been restricted since 1985. As a result of this restriction and protection of immature individuals, spawning stock biomass (SSB) recently has shown a slight increase. The Commission for the Conservation of Southern Bluefin Tuna (CCSBT) has the target of recovering SSB to the 1980 level by 2020. We investigated whether SBT populations will recover and reach the target level set by CCSBT. Our projection shows that the SSB of the SBT will temporarily decrease again after 1999. This temporary decrease of SSB does not always mean failure of the recovery plan, because the SSB trend is highly vulnerable to age-composition dynamics. The SBT is an example of this. The number of mature SBT was small during the 1980s because of overfishing. Thus, the number of eggs that were spawned by these mature SBT was small in these years, and when these small numbers of immature fish become mature, the SSB will decrease again. We call this effect the inverse baby-boom effect. The inverse baby-boom effect may be common for managed bioresources that have once been overexploited. We also examine the use of spawning potential (SP) and SSB as an index of stock recovery. Received: August 17, 2000 / Accepted: March 19, 2001