A new species of Eugenia (Myrtaceae) from south‐eastern Brazil

A new species, Eugenia marambaiensis M.C.Souza & M.P.Morim, is described and illustrated. It is characterized by having large translucent gland dots densely distributed on the leaves, with a caudate apex and slightly wavy margins and a glabrous raceme, with only two flowers. Eugenia marambaiensis was only found in the locality of Restinga da Marambaia, Rio de Janeiro, Brazil. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 306–308.     

胞外ATP对AlCl3诱导的细胞死亡过程中胞内H2O2和Ca2+水平的影响及其生理机制分析

该实验以烟草悬浮细胞 BY 2 为材料,在烟草悬浮细胞中分别加入0.05、0.10、0.15、0.20 mmol·L^-1AlCl₃,以等体积去离子水处理的悬浮细胞液为对照,并依据前述实验结果选择0.15 mmol·L^-1 AlCl₃,分别添加5 mmol·L^-1 DMTU(H₂O₂ 抑制剂)、20 μmol·L^-1CaCl₂、15 μmol·L^-1 LaCl₃(Ca²⁺通道抑制剂)和50 μmol·L^-1 ATP设计多项处理,分析胞外ATP(eATP)对铝离子(Al³⁺)胁迫引起的植物细胞死亡及其胞内H₂O₂、Ca²⁺的影响,以揭示Al³⁺胁迫下植物调节细胞死亡的可能机制,进一步扩展对eATP功能的认知。结果显示：(1)随着 AlCl₃ 胁迫浓度的提高,细胞死亡水平和胞内H₂O₂水平上升,而胞内Ca²⁺和eATP水平则逐渐降低。(2)外援施加H₂O₂抑制剂 DMTU(二甲基硫脲)和Ca²⁺能够有效缓解AlCl₃诱导的细胞死亡水平的上升;而Ca²⁺通道抑制剂LaCl₃(三氯化镧)则加剧了AlCl₃胁迫下的细胞死亡。(3)在AlCl₃胁迫下对细胞添加外源ATP,能够缓解AlCl₃胁迫下胞内H₂O₂水平上升和Ca²⁺水平下降的同时,并显著降低AlCl₃胁迫导致的细胞死亡。研究表明, Al³⁺以剂量依赖的模式提升细胞死亡和细胞内H₂O₂的水平并降低胞内Ca²⁺和eATP水平,AlCl₃诱导的细胞死亡受到H₂O₂和Ca²⁺水平变化的调节,eATP可以通过调节H₂O₂与Ca²⁺水平缓解AlCl₃诱导的细胞死亡。推测Al³⁺胁迫可能通过抑制钙离子通道而破坏了细胞内H₂O₂和Ca²⁺之间的协同关系,外源ATP对Al³⁺诱导H₂O₂上升的缓解作用可能是由于其提升了细胞的抗氧化能力。     

Total sleep deprivation does not significantly degrade semantic encoding

ABSTRACT

Sleep deprivation impairs performance on cognitive tasks, but it is unclear which cognitive processes it degrades. We administered a semantic matching task with variable stimulus onset asynchrony (SOA) and both speeded and self-paced trial blocks. The task was administered at the baseline and 24 hours later after 30.8 hours of total sleep deprivation (TSD) or matching well-rested control. After sleep deprivation, the 20% slowest response times (RTs) were significantly increased. However, the semantic encoding time component of the RTs remained at baseline level. Thus, the performance impairment induced by sleep deprivation on this task occurred in cognitive processes downstream of semantic encoding.     

High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups

We recently proposed that patterns of evolution of non-LTR retrotransposable elements can be used to study patterns of spontaneous mutation. Transposition of non-LTR retrotransposable elements commonly results in creation of 5' truncated, "dead-on-arrival" copies. These inactive copies are effectively pseudogenes and, according to the neutral theory, their molecular evolution ought to reflect rates and patterns of spontaneous mutation. Maximum parsimony can be used to separate the evolution of active lineages of a non-LTR element from the fate of the "dead-on-arrival" insertions and to directly assess the relative frequencies of different types of spontaneous mutations. We applied this approach using a non-LTR element, Helena, in the Drosophila virilis group and have demonstrated a surprisingly high incidence of large deletions and the virtual absence of insertions. Based on these results, we suggested that Drosophila in general may exhibit a high rate of spontaneous large deletions and have hypothesized that such a high rate of DNA loss may help to explain the puzzling dearth of bona fide pseudogenes in Drosophila. We also speculated that variation in the rate of spontaneous deletion may contribute to the divergence of genome size in different taxa by affecting the amount of superfluous "junk" DNA such as, for example, pseudogenes or long introns. In this paper, we extend our analysis to the D. melanogaster subgroup, which last shared a common ancestor with the D. virilis group approximately 40 MYA. In a different region of the same transposable element, Helena, we demonstrate that inactive copies accumulate deletions in species of the D. melanogaster subgroup at a rate very similar to that of the D. virilis group. These results strongly suggest that the high rate of DNA loss is a general feature of Drosophila and not a peculiar property of a particular stretch of DNA in a particular species group.      

Tropomyosin is localized in the nuclear matrix and chromosome scaffold of physarum polycephalum

The nuclei and chromosomes were isolated from plasmodia of Physarum polycephalum.The nuclear matrix and chromosome scaffold were obtained after the DNA and most of the proteins were extracted with DNase I and 2 M NaCl.SD-PAGE analyses revealed that the nuclear matrix and chromosome scaffold contained a 37 kD polypeptide which is equivalent to tropomyosin in molecular weight.Immunofluorescence observations upon slide preparations labeled with anti-tropomyosin antibody showed that the nuclear matrix and chromosome scaffold emanated bright fluorescence,suggesting the presence of the antigen in them.Immunodotting results confirmed the presence of tropomyosin in the nuclear matrix and chromosome scaffold.Immunoelectron microscopic observations further demonstrated that tropomyosin was dispersively distributed in the interphase nuclei and metaphase chromosomes.     

小鼠淋巴细胞抗原CTLA-4的胞外肽段表达及纯化

目的: 真核细胞表达小鼠淋巴细胞抗原CTLA-4胞外段肽,研究表达肽段与抗原呈递细胞B7分子结合后减轻小鼠淋巴细胞刺激后的增殖抑制,从而启动T淋巴细胞进一步增殖。方法:从小鼠脾脏淋巴细胞获得总RNA,通过逆转录PCR扩增出CTLA-4全长基因,克隆并测序。依据胞外段序列和真核表达载体pcDNA3.1序列,合成引物扩增胞外片段,两者经内切核酸酶处理、连接构建重组表达pcDNA3.1载体,重组质粒经测序验证后,采用lipofectamine 2000转染入小鼠肝癌细胞Hepa1-6,经G418筛选获得稳定表达细胞株。结果:获得小鼠CTLA-4胞外段真核表达载体和小鼠肝癌细胞Hepa1-6稳定表达转染细胞株,制备了CTLA-4胞外肽段,经His标签抗体和小鼠CTLA-4抗体Western blot检测表达蛋白带均呈阳性。结论:获得CTLA-4胞外段肽,为进一步研究该肽的作用打下基础。     

Morphology and development of additional bony elements in the genus Brachycephalus (Anura: Brachycephalidae)

We describe the extra bony elements, plates, and osteoderms present in species of the genus Brachycephalus. Samples of eight species of Brachycephalus, including seven populations of Brachycephalus ephippium, were examined. The large additional elements associated with the skull (parotic plate) and vertebrae (vertebral and paravertebral plates) all comprise intramembranous bone, similar to that of the frontoparietal or nasal bones of the skull of most of frogs. Additionally, in the dermis of one unnamed species, we discovered and described true osteoderms. We discuss the morphological nature and diversity of theses elements and their importance as evidence of phylogenetic relationship within Brachycephalus. In summary, three distinct conditions of extra bony elements occur in the genus Brachycephalus: (1) bony plates may be present or absent in species of the genus; (2) a few, small bony plates may be developed and these may be represented by (a) paravertebral plates small and restricted to the distal ends of the transverse processes of the presacral IV, (b) parotic plates small and not covering the tops of the squamosals, and (c) ornamented spinal plates on all vertebrae; and (3) well‐developed bony plates may be present as (a) paravertebral plates forming a ‘bone‐shield’ on the dorsal surface of the trunk, ornamented, and visible through the integument, (b) parotic plates covering the tops of the squamosals, and (c) spinal plates associated with all vertebrae, and ornamented on vertebrate I–VI. Although the phenomenon of miniaturization may be associated with the appearance of new elements in at least some of the species in the genus, the traditional rule may not be universally applicable. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 752–767.     

An IGF-I promoter polymorphism modifies the relationships between birth weight and risk factors for cardiovascular disease and diabetes at age 36

BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.