不同环境下籼型杂交稻穗干物质重的发育遗传分析

选用穗干物质重性状差异较大的 4个籼型不育系 (A)和相应的保持系 (B)以及 5个籼型恢复系(R) ,按不完全双列杂交设计 (4× 5 ) ,配成一套亲本和F12个世代的遗传群体 .采用包括基因型×环境互作的加性 显性发育遗传模型 ,分析了两年的籼型杂交稻不同发育时期穗干物质重的遗传表现 .结果表明 ,穗干物质重的发育全过程均受到遗传主效应和基因型与环境互作效应的控制 .在穗干物质重发育的前、中期 (15d前 )主要由显性效应控制 ,显性效应基因的表达量最大 ,环境因素的正向影响也较明显 ,可通过采取适当的栽培管理措施为稻穗发育创造良好的环境条件 ,促进杂种优势潜力的充分发挥 ;在发育的中后期 (15d后 )加性效应转为主要作用 ,加性效应基因的表达也呈最活跃状态 ,这一时期对穗重进行遗传选择会获得较好的遗传进度 .     

Seasonal variations in the chemical composition and dry matter degradability of exclosure forages in the semi-arid region of northern Ethiopia

The present study was conduced at two sites (Tembien and Wukro) in the semi-arid region of Tigray in northern Ethiopia to investigate the seasonal dynamics in the chemical composition and dry matter digestibility of grass and browse species of exclosures. The browse species studied in Tembien and Wukro had a mean crude protein (CP) value of 166 and 117 g/kg dry matter (DM), respectively. The mean in vitro dry matter digestibility (IVDMD) coefficient and predicted metabolizable energy (ME) density of the browse species were 0.72 and 9.83 MJ/kg DM, respectively at Tembien, 0.62 and 8.38 MJ/kg DM, respectively, at Wukro. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) values of the browse species varied from 192 to 437 and 127 to 391 g/kg DM, respectively. Acid detergent lignin (ADL) values ranged from 36 to 190 g/kg DM. The mean CP of the grass species in Tembien and Wukro during the long rainy season was 76 and 73 g/kg DM, respectively and values declined below a critical maintenance level during the dry and short rain seasons. Mean IVDMD and ME values for the two sites were 0.41 and 0.47, and 5.38 and 6.11 MJ/kg DM, respectively. The NDF, ADF, and lignin values of the grass species were generally above 700, 400, and 70 g/kg DM, respectively. The CP, IVDMD and ME values of the mixed grass samples differed (P<0.05) among harvesting months and values ranged from 20 to 103 g/kg DM, 0.47 to 0.72 MJ/kg DM, and 6.16 to 9.91 MJ/kg DM, respectively. The browse species could be used as useful dry season protein supplements to the N deficient native grass species. Especial emphasis should be given to propagate Maerua angolensis and Cadaba farinosa at community nursery sites. Harvesting in September, rather than the current extended harvest period that took place in October and November, can considerably improve the feeding value of native grass hay for smallholder ruminant production systems.     

Comparison of the folding mechanism of highly homologous proteins in the lipid‐binding protein family

The folding mechanism of two closely related proteins in the intracellular lipid‐binding protein family, human bile acid‐binding protein (hBABP), and rat bile acid‐binding protein (rBABP) were examined. These proteins are 77% identical (93% similar) in sequence. Both of these single domain proteins fit well to a two‐state model for unfolding by fluorescence and circular dichroism at equilibrium. Three phases were observed during the unfolding of rBABP by fluorescence but only one phase was observed during the unfolding of hBABP, suggesting that at least two kinetic intermediates accumulate during the unfolding of rBABP that are not observed during the unfolding of hBABP. Fluorine NMR was used to examine the equilibrium unfolding behavior of the W49 side chain in 6‐fluorotryptophan‐labeled rBABP and hBABP. The structure of rBABP appears to be more dynamic than that of hBABP in the vicinity of W49 in the absence of denaturant, and urea has a greater effect on this dynamic behavior for rBABP than for hBABP. As such, the folding behavior of highly sequence related proteins in this family can be quite different. These differences imply that moderately sized proteins with high sequence and structural similarity can still populate quite different structures during folding. Proteins 2009. © 2008 Wiley‐Liss, Inc.     

Pollination biology of the sclerophyllous shrub Pultenaea villosa Willd. (Fabaceae) in southeast Queensland, Australia

The pollination biology of the common shrub Pultenaea villosa Willd. was examined in a subtropical dry sclerophyll forest in eastern Australia. We determined floral phenology and morphology, the timing of stigma receptivity and anther dehiscence, nectar availability, the plant breeding system, and flower visitors. The shrub's flowers are typical zygomorphic pea flowers with hidden floral rewards and reproductive structures. These flowers require special manipulation for insect access. A range of insects visited the flowers, although bees are predicted to be the principle pollinators based on their frequency on the flowers and their exclusive ability to operate the wing and keel petals to access the reproductive structures. Nectar and pollen are offered as rewards and were actively collected by bees. Nectar is offered to visitors in minute amounts at the base of the corolla. In Toohey Forest, P. villosa flowers in spring and is the most abundant floral resource in the understory of the forest at this time. The breeding system experiment revealed that P. villosa requires outcrossing for high levels of seed set and that the overlap of stigma receptivity and pollen dehiscence within the flower suggests the potential for self-incompatibility.     

A single mutation induces molten globule formation and a drastic destabilization of wild-type cytochrome c at pH 6.0

Amino acid sequences of seven subfamilies of cytochromes c show that other than heme binding residues there are only four positions which are conserved in all subfamilies: Gly/Ala6, Phe/Tyr10, Leu/Val/Phe94, and Tyr/Trp/Phe97. These residues are 90% conserved in all sequences reported and are also considered to be involved in a common folding nucleus. To determine the importance of conserved interactions offered by the side chain of Leu94, we made an L94G mutant of horse cytochrome c. Characterization of this mutant by the far-UV, near-UV, and Soret circular dichroism, intrinsic and 1-Anilino-8-naphthalene sulfonate fluorescence, and dynamic light scattering measurements led to the conclusion that the L94G mutant has all the common structural characteristics of a molten globule at pH 6.0 and 25 °C. NaCl induces a cooperative transition between the acid-denatured state and a state of L94G having all the common structural characteristics of a pre-molten-globule state at pH 2 and 25 °C. Thermal denaturation studies showed that the midpoint of denaturation of the mutant is 28 °C less than that of the wild-type protein. Interestingly, the structure analysis using the coordinates given in the Protein Data Bank (1hrc) also suggested that the L94G mutant would be less stable than the wild-type protein.     

环境胁迫对岷江干旱河谷豆科灌木幼苗根系生长及其结瘤的影响

通过野外调查,分析了岷江干旱河谷海拔梯度上相同年龄段的白刺花、岷谷木蓝和小雀花幼苗根系结瘤、生物量积累、生物量百分比的变化及其相互关系;人为控制土壤水分（田间持水量(WHC)的80%、60%、40%和20% 4个水平）研究了干旱对2月龄的白刺花与小雀花幼苗结瘤能力的影响.结果表明：1)干旱河谷低海拔地段(1600～1950 m)幼苗的结瘤能力都很低,白刺花、岷谷木蓝和小雀花的平均结瘤数分别为每株(0.1±0.1)、(0.9±0.5)和(5.7±1.9)个,未结瘤的个体分别占651%、123%和176%;总体上随着海拔的升高,3种幼苗的根瘤数均呈增加趋势,且与细根百分比及根长正相关.2)土壤水分低于60% WHC时,白刺花与小雀花的根瘤数及生物量均明显减小;在20% WHC条件下,白刺花根瘤数为0,小雀花根瘤数为每株(9.8±3.6)个.综合分析发现,干旱河谷地区豆科灌木的结瘤固氮能力很低,土壤水分在40% WHC以上时其生物固氮才能有效发挥,与白刺花相比,小雀花结瘤能力较高,干旱忍受性较强.     

Development and characterization of 11 microsatellite markers in a widespread Neotropical seasonally dry forest tree species,Geoffroea spinosa Jacq. (Leguminosae)

Eleven dinucleotide microsatellites were developed in Geoffroea spinosa (Leguminosae), a widespread tree of the seasonally dry Neotropical forests, and characterized on six populations from Peru, Argentina and Paraguay. Four of them amplified on the Peruvian populations only, probably because of mutations in the microsatellite flanking regions in the other populations. Ten microsatellites were found polymorphic, with within population gene diversities ranging from 0.17 to 0.95, and a number of alleles varying from seven to 19. A significant overall genetic differentiation was also found (θ = 0.212; P < 0.01).     

“El Niño” events recorded in dry-forest species of the lowlands of northwest Peru

The northwest coast of Peru (5°S, 80°W) is very sensitive to and impacted by the climate phenomenon El Niño-Southern Oscillation (ENSO). Though mainly desert, this warm, dry region contains an equatorial dry forest. We report the first dendrochronological studies from this region and identify several species that have dendrochronological potential. Short ring-width chronologies of Palo Santo (Bursera graveolens) show a well-developed response to the ENSO signal over the last 50 years and good inter-site correlations. Preliminary isotopic studies in Algarrobo (Prosopis sp.) also show evidence of the 1997–98 El Niño event. ENSO events have a strong effect on the variability in the growth of several species and thereby on the economy of rural communities where the wood is used for housing, cooking, furniture, tools, fodder and medicinal uses. The extensive use of wood in archeological sites also offers the possibility of ultimately developing longer records for some of these species.     

Spatial distribution and trophic ecology of dominant copepods associated with turbidity maximum along the salinity gradient in a highly embayed estuarine system in Ariake Sea, Japan

The present study aimed to investigate into the feeding ecology of the dominant copepods along a salinity gradient in Chikugo estuary. Copepod composition was studied from samples collected from stations positioned along the salinity gradient of the estuary. Copepod gut pigment concentrations were measured by fluorescence technique and hydrographical parameters such as temperature, salinity, transparency, suspended particulate matter (SPM); pigments such as chlorophyll-a (Chl-a), phaeopigment; and particulate nutrients such as particulate organic carbon (POC) and particulate organic nitrogen (PON) were measured. Two distinct zones in terms of nutrient and pigment concentrations as well as copepod distribution and feeding were identified along the estuary. We identified a zone of turbidity maximum (TM) in the low saline upper estuary which was characterized by having higher SPM, higher POC and PON but lower POC:PON ratios, higher pigment concentrations but lower Chl-a/SPM ratios and higher copepod dry biomass. Sinocalanus sinensis was the single dominant copepod in low saline upper estuary where significantly higher concentrations of nutrients and pigments were recorded and a multispecies copepod assemblage dominated by common coastal copepods such as Acartia omorii, Oithona davisae and Paracalanus parvus was observed in the lower estuary where nutrient and pigment concentrations were lower. Copepods in the estuary are predominantly herbivorous, feeding primarily on pigment bearing plants. However, completely contrasting trophic environments were found in the upper and the lower estuary. It was speculated from the Chl-a and phaeopigment values that copepods in the upper estuary receive energy from a detritus-based food web while in the lower estuary an algal-based food web supports copepod growth. Overall, the upper estuary was identified to provide a better trophic environment for copepod and is associated with higher SPM concentrations and elevated turbidity. The study demonstrates the role of estuarine turbidity maximum (ETM) in habitat trophic richness for copepod feeding. The study points out the role of detritus-based food web as energy source for the endemic copepod S. sinensis in the upper estuary, which supports as nursery for many fish species.     

雅砻江和大渡河干旱河谷植被物种多样性比较:气候、地形与空间的影响

干旱河谷植被是我国西南横断山区的一类特殊的隐域性生态系统, 影响不同河谷之间植物群落差异的因素与作用大小尚不清楚。本研究调查了四川省雅砻江和大渡河流域干旱河谷段植被组成, 并比较了两个地区在植物多样性上的差别。结果表明: (1)影响两个地区植被类型的主要因素不同, 雅砻江干旱河谷植被主要受海拔和地形(坡度和坡向)影响, 大渡河干旱河谷植被主要受年平均降水量影响。(2)雅砻江和大渡河干旱河谷植物物种丰富度均随着年均温升高而降低。(3)坡向由北至南, 雅砻江干旱河谷灌木、草本物种丰富度减小, 而大渡河干旱河谷灌木、草本丰富度增加。(4)坡度越大, 雅砻江和大渡河干旱河谷灌木的丰富度越高。(5)雅砻江、大渡河干旱河谷植物β多样性受环境距离影响大, 受地理距离影响小。两条江植被间地理隔离效应约为地理距离产生差异的5倍。本研究弥补了干旱河谷研究中对于雅砻江和大渡河干旱河谷植物多样性研究的空白, 为相关区域植被保护提供了参考信息, 同时还为定量估计地理隔离效应对区域间生物多样性差异的影响提供了可行方法。