Age‐specific variation in relationship between moult and pre‐migratory fuelling in Wood Sandpipers Tringa glareola in southern Africa

Trans‐equatorial avian migrants tend to breed, moult and migrate – the main energy‐requiring events in their lifecycle – at different times. Little is known about the relationship between wing moult and pre‐migratory fuelling in waders on their non‐breeding grounds, where time is less constrained than during their brief high‐latitude breeding season. We determined age‐related strategies of Wood Sandpipers Tringa glareola to balance the energetic demands of primary moult against pre‐migratory fuelling in southern Africa by analysing body mass and primary moult at first capture of 1721 birds mist‐netted in 1972–96 at waterbodies in Zimbabwe. Adults moulted all their primaries in August–December, but immatures underwent a supplemental moult of varying numbers of outer primaries in December–April, close to departure. We used locally weighted linear regression to estimate trends in Wood Sandpiper body mass from 1 July to 1 May. They maintained low mass from arrival in July–September to February–early March. Adults fuelled from 10 February to 1 May at a mean rate of 0.25 g/day (sd = 0.16). Most adults (98%) began fuelling 10–75 days after completing primary moult. Immatures fuelled from 4 March to 13 April at 0.24 g/day (sd = 0.14). They used varying strategies depending on their condition: a brief gap between moult and fuelling; an overlap of these processes near departure, leading to slower fuelling; or skipping fuelling altogether and staying in southern Africa for a ‘gap year’. Immatures moulting three or five outer primaries fuelled more slowly than post‐moult birds. Immatures moulting four outer primaries started fuelling 3 weeks later but at a higher rate than did post‐moult birds of this group. In post‐moult immatures, the later they ended moult, the later and faster they fuelled. The heaviest adults and immatures using all moult patterns accumulated fuel loads of c. 50% of lean body mass, and could potentially cross 2397–4490 km to reach the Great Rift Valley in one non‐stop flight. Immatures were more flexible in the timing and extent of moult and in the timing and rate of fuelling than adults. This flexibility enables inexperienced Wood Sandpipers to cope with inter‐annual differences in feeding conditions at Africa's ephemeral inland waterbodies.     

二色补血草LbDREB基因在酵母中的抗逆性分析

利用酵母表达系统研究了二色补血草的DREB基因（LbDREB）对不同胁迫的抗性。将LbDREB构建到酵母表达载体pYES2中,转化到酿酒酵母INVSc1菌株中,并以转空pYES2质粒的酵母INVSc1（pYES2）作为对照,通过比较两种酵母在不同胁迫下的存活率来研究LbDREB基因对NaCl、KH_2PO_4、Na_2CO_3、NaHCO_3、低温、干旱、CuSO_4和CdCl_2胁迫的抗性。结果表明,LbDREB转化的酵母在各种胁迫下的存活率均明显高于转空pYES2的对照酵母,说明LbDREB基因除了具有传统认为的抗旱、耐盐、抗寒的作用外,还具有抗KH_2PO_4、Na_2CO_3、NaHCO_3、CuSO_4和CdCl_2等胁迫的能力。     

NOTES ON THE CAPRIMULGIDAE OF THE KAFUE BASIN

During 2002–2007, we assessed the status of the Purple Heron Ardea purpurea in Numidia, Algeria by surveying all the major wetlands in the region. We located six distinct breeding sites; four of these were not previously known. We also investigated nest site selection and determined the species’ reproductive success at Dakhla, a dunary pond during two successive years (2006 and 2007). The egg laying period was comparable to that reported for southern Europe (March-May) and a seasonal change of breeding success was recorded. A growth curve was derived for developing nestlings and the impact of an ectoparasite (mite) infestation upon nestling's growth was considered. We also examined 73 food boluses regurgitated by nestlings and identified 329 prey items. Fish, mainly Gambusia holbrookii and Cyprinus carpio, dominated by mass, whereas insects, mainly aquatic Coleopteran larvae and aeshnids (Odonata), were the most frequent prey (67.1%). Loss of habitat is identified as a major threat to the future of colonial herons in Algeria.     

Sex Determination: Why So Many Ways of Doing It?

Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination.     

实时荧光定量分析小黑杨应拉木相关基因及转录因子的表达

利用实时定量RT-PCR技术,比较了不同时期小黑杨应拉木中与木材形成相关的基因及其转录因子的表达模式。研究结果表明,与纤维素合成相关的基因如纤维素合成酶基因（CesA）、蔗糖合成酶基因（SUSY）、ACC氧化酶基因（ACO）等基因胁迫后在弯曲茎的上侧中表达量高于其在弯曲茎的下侧中的表达;尤其是FLA基因家族在弯曲茎的上侧中大量表达,而在弯曲茎的下侧中几乎不表达。与之相反,与木质素合成相关的基因如咖啡酰辅酶A-O-甲基转移酶（CCoAOMT）、苯丙氨酸裂解酶（PAL）、漆酶（laccase）、过氧化物酶（POD）等基因在弯曲茎的上侧中表达量低而在弯曲茎的下侧中表达量高,转录因子MYB基因在弯曲茎的上侧中表达量高于其在弯曲茎的下侧中的。     

赤桉抗寒转录因子ICE1基因的分子克隆与表达分析

ICE1属于一种类似MYC的bHLH转录因子,可特异地结合到CBF3启动子的MYC作用元件并诱导CBF/DREB1下游基因的转录表达。本文以拟南芥ICE1蛋白序列为信息探针,搜索桉树基因组和EST数据库的同源序列并进行拼接、设计引物,通过RT-PCR从赤桉克隆了桉树的第一个ICE1基因。其cDNA长1792bp,含有完整的开放阅读框,可编码523个氨基酸。BLAST分析表明,cDNA序列及其推导的氨基酸序列均与拟南芥、芥菜、小麦和甜杨ICE1存在着较高的同源性,预示所获得的cDNA可能是赤桉ICE1基因（EcaICE1）。EcaICE1基因表达分析结果显示,EcaICE1在赤桉根、茎、叶中均表达,而且表达水平不受低温胁迫处理时间的影响,这表明EcaICE1是组成型表达。此外,EcaICE1的超表达可以提高转基因烟草的耐低温能力。上述结果为进一步研究EcaICE1在赤桉耐低温胁迫过程中基因表达的调控机制打下基础。