Natal dispersal in great bustards: the effect of sex, local population size and spatial isolation

1. We investigated the causes of natal dispersal in four Spanish areas where 35 breeding groups of the polygynous great bustard Otis tarda were monitored intensively. A total of 392 juveniles were radio-tracked between 1991 and 2006 by ground and via aeroplane to avoid potential biases derived from the non-detection of long-distance dispersers. 2. We explored 10 explanatory variables that were related to individual phenotypic features, habitat and conspecific traits in terms of group size and breeding performance, and spatial distribution of available breeding groups. Probability of group change and natal dispersal distances were investigated separately through multifactorial analyses. 3. Natal dispersal occurred in 47.8% of the birds and median natal dispersal distance of dispersers was 18.1 km (range 4.97-178.42 km). Sex largely determined the dispersal probability, with 75.6% of males being dispersers and 80.0% of females being philopatric, in contrast to the general pattern of female-biased dispersal found in most avian species. 4. Both the frequency of natal dispersal and dispersal distances were affected by the spatial distribution of breeding groups. More isolated groups showed a higher proportion of philopatric individuals, the effect being more evident in males than in females. This implies a reduction in gene flow in fragmented populations, as most genetic exchange is achieved through male dispersal. Additionally, dispersers hatched in more isolated groups tended to exhibit longer dispersal distances, which increases the associated energetic costs and mortality risks. 5. The dispersal decision was influenced by the number of conspecifics in the natal group. The individual probability of natal dispersal was related inversely to the size of the natal group, which supports the balanced dispersal model and the conspecific attraction hypothesis. 6. Overall, our results provide a good example of phenotypic plasticity and reinforce the current view that dispersal is an evolutionary complex trait conditioned by the interaction of individual, social and environmental causes that vary between individuals and populations.     

笼养条件的改变对大鸨繁殖期行为的影响

2002～2004年4～6月,采用瞬时扫描法对哈尔滨动物园饲养的16只（5♂,11♀）大鸨（Otis tarda）的繁殖期行为进行了观察。利用非参数检验法讨论了笼舍面积、舍内设计及外界噪音对大鸨繁殖期的行为分配、日节律、炫耀及一些特殊行为的影响。结果表明,环境因子对大鸨繁殖期行为存在显著影响,当环境条件改变后,大鸨的警戒行为发生显著变化（P〈0．01）,其次为炫耀、游走行为（P〈0．05）。另外,环境因子的变化对雄性大鸨的炫耀路线及求偶方式亦存在影响,同时影响沙浴等特殊行为。     

Characterization of the rrn operons in the channel catfish pathogen Edwardsiella ictaluri

Aims:  To advance diagnostics and phylogenetics of Edwardsiella ictaluri by sequencing and characterizing its rrn operons.
Methods and results:  The Edw. ictaluri rrn operons were identified from a 5–7 kbp insert lambda library and from Edw. ictaluri fosmid clones. We present the complete sequences and analysis of all eight Edw. ictaluri rrn operons and unique regions located upstream and downstream. Two rrn operons were located in tandem with 169 bp separating them, which is apparently a conserved feature between Edw. ictaluri and Edwardsiella tarda. I- Ceu I enzyme digestion of Edw. ictaluri genomic DNA and analysis by pulsed field gel electrophoresis indicated that rrn operon number and chromosomal locations are conserved within the species Edw. ictaluri .
Conclusions:  The rrn operons of Edw. ictaluri have similar structure and flanking regions compared with other members of the family Enterobacteriaceae ; however, the presence of eight copies of the rrn operon makes Edw. ictaluri unique within the family .
Significance and impact of the study:  This research clarifies previous phylogenetic analyses of Edw. ictaluri and provides support for the Edw. ictaluri genome sequencing project. In addition, we identified a unique feature of two rrn operons that shows potential for the development of a diagnostic PCR method.     

先天性红细胞生成性卟啉症患者酶活性的研究

先天性红细胞生成性卟啉症（ｃｏｎｇｅｎｉｔａｌｅｒｙ－ｔｈｒｏｐｏｉｅｔｉｃｐｏｒｐｈｙｒｉａ,ＣＥＰ）是Ｇｕｎｔｈｅｒ于１９１１年首先提出并加以描述,有时亦称Ｇｕｎｔｈｅｒ病．该病是因遗传性缺陷所致卟啉代谢中有关酶的异常造成的卟啉代谢紊乱而发生的一...     

内蒙古图牧吉大鸨种群动态及时空分布稳定性

大鸨（Otis tarda）是我国I级重点保护野生鸟类,对大鸨重要栖息地种群数量的变化趋势进行研究,将为大鸨及其栖息地的保护提供科学依据。2017年至2020年,对内蒙古图牧吉国家级自然保护区内及周边的大鸨种群数量动态进行了全面调查,共选择33个监测地点,对大鸨的数量、性别和分布地点进行了调查。结果表明,大鸨种群数量从2017年193只增加至2020年253只;大鸨1月的越冬种群数量从2017年67只减少至2019年55只,2020年重新恢复至67只。各月大鸨种群数量呈现较大的变化,数量高峰期分别是5月和10月。12月至次年2月,越冬种群数量50 ~ 70只。雌性大鸨从3月开始监测到,数量高峰值出现在4月和5月,达到50 ~ 70只,不同的年份略有差别;6月之后数量开始下降,至9月开始略有回升,在10月以后,野外基本观察不到雌性个体。在野外易于观察的4月,2017至2020年4年中雌雄比的平均值是1︰2。2017年和2018年,大鸨在马鞍山区域分布较多,数量也较为稳定。然而进入2019年,分布地点减少,这可能与当地人类活动的干扰有关;2020年保护区功能区进行了调整,将2014年调整出保护区范围的马鞍山区域重新划入保护区中,湿地和草地面积均有所增加,大鸨分布地点数量逐渐恢复。针对目前保护区存在的问题,建议采取退耕还草、加强保护空缺管理及禁牧等保护措施对大鸨及其栖息地进行保护。     

Immunoanalysis of calf uterine progesterone receptor: Modulation of receptor-associated 90 kDa heat-shock protein

Porphyrias are inherited and acquired diseases of erythroid or hepatic origin, in which there are defects in specific enzymes of the heme biosynthetic pathway. In patients with intermittent acute porphyria and lead poisoning the erythrocytic activities of superoxide dismutase and glutathione peroxidase are reported to be increased. Our studies demonstrated that d-aminolevulinic acid, a heme precursor accumulated in both diseases, undergoes enolization at pH < 7.0 before it autoxidizes. The autoxidation of d-aminolevulinic acid, in the presence or absence of oxyhemoglobin has been proposed as a source of oxy and carbon-centred radicals in the cells of intermittent acute porphyria and saturnism carriers. Thus, the increased levels of antioxidant enzymes can be viewed as an intracellular response against the deleterious effects of these extremely reactive species.     

迟缓爱德华氏菌对Hep-2细胞的侵袭特性

用细胞裂解计数法及超薄切片电镜观察法分析了迟缓爱德华氏菌侵袭ＨＥｐ－２细胞的基本特性。在１５株来源各异的迟缓爱德华氏菌中,有６株细菌具有对ＨＥｐ－２细胞的侵袭能力。细菌侵入细胞后,主要位于空泡内。侵入细胞内的迟缓爱德华氏菌不仅可在细胞内增殖,而且可从细胞内释放出来。用细胞松弛素破坏微丝后可抑制其侵袭作用,而且表现出剂量依赖关系,而在秋水仙素破坏微管后不影响其侵袭力。这表明在迟缓爱德华氏菌对ＨＥｐ－     

Multiple roles of haem in cystathionine β-synthase activity: implications for hemin and other therapies of acute hepatic porphyria

The role of haem in the activity of cystathionine β-synthase (CBS) is reviewed and a hypothesis postulating multiple effects of haem on enzyme activity under conditions of haem excess or deficiency is proposed, with implications for some therapies of acute hepatic porphyrias. CBS utilises both haem and pyridoxal 5′-phosphate (PLP) as cofactors. Although haem does not participate directly in the catalytic process, it is vital for PLP binding to the enzyme and potentially also for CBS stability. Haem deficiency can therefore undermine CBS activity by impairing PLP binding and facilitating CBS degradation. Excess haem can also impair CBS activity by inhibiting it via CO resulting from haem induction of haem oxygenase 1 (HO 1), and by induction of a functional vitamin B₆ deficiency following activation of hepatic tryptophan 2,3-dioxygenase (TDO) and subsequent utilisation of PLP by enhanced kynurenine aminotransferase (KAT) and kynureninase (Kynase) activities. CBS inhibition results in accumulation of the cardiovascular risk factor homocysteine (Hcy) and evidence is emerging for plasma Hcy elevation in patients with acute hepatic porphyrias. Decreased CBS activity may also induce a proinflammatory state, inhibit expression of haem oxygenase and activate the extrahepatic kynurenine pathway (KP) thereby further contributing to the Hcy elevation. The hypothesis predicts likely changes in CBS activity and plasma Hcy levels in untreated hepatic porphyria patients and in those receiving hemin or certain gene-based therapies. In the present review, these aspects are discussed, means of testing the hypothesis in preclinical experimental settings and porphyric patients are suggested and potential nutritional and other therapies are proposed.     

Protein-aggregating ability of different protoporphyrin-IX nanostructures is dependent on their oxidation and protein-binding capacity

Porphyrias are rare blood disorders caused by genetic defects in the heme biosynthetic pathway and are associated with the accumulation of high levels of porphyrins that become cytotoxic. Porphyrins, due to their amphipathic nature, spontaneously associate into different nanostructures, but very little is known about the cytotoxic effects of these porphyrin nanostructures. Previously, we demonstrated the unique ability of fluorescent biological porphyrins, including protoporphyrin-IX (PP-IX), to cause organelle-selective protein aggregation, which we posited to be a major mechanism by which fluorescent porphyrins exerts their cytotoxic effect. Herein, we tested the hypothesis that PP-IX-mediated protein aggregation is modulated by different PP-IX nanostructures via a mechanism that depends on their oxidizing potential and protein-binding ability. UV–visible spectrophotometry showed pH-mediated reversible transformations of PP-IX nanostructures. Biochemical analysis showed that PP-IX nanostructure size modulated PP-IX-induced protein oxidation and protein aggregation. Furthermore, albumin, the most abundant serum protein, preferentially binds PP-IX dimers and enhances their oxidizing ability. PP-IX binding quenched albumin intrinsic fluorescence and oxidized His-91 residue to Asn/Asp, likely via a previously described photo-oxidation mechanism for other proteins. Extracellular albumin protected from intracellular porphyrinogenic stress and protein aggregation by acting as a PP-IX sponge. This work highlights the importance of PP-IX nanostructures in the context of porphyrias and offers insights into potential novel therapeutic approaches.