Mitochondrial DNA diversity in South America and the genetic history of Andean highlanders

We analyzed mtDNA sequence variation in 590 individuals from 18 south Amerindian populations. The spatial pattern of mtDNA diversity in these populations fits well the model proposed on the basis of Y-chromosome data. We found evidence of a differential action of genetic drift and gene flow in western and eastern populations, which has led to genetic divergence in the latter but not in the former. Although it is not possible to identify a pattern of genetic variation common to all South America, when western and eastern populations are analyzed separately, the mtDNA diversity in both regions fits the isolation-by-distance model, suggesting independent evolutionary dynamics. Maximum-likelihood estimates of divergence times between central and south Amerindian populations fall between 13,000 and 19,000 years, which is consistent with a Pleistocenic peopling of South America. Moreover, comparison of among-population variability of mtDNA and Y-chromosome DNA seems to indicate that South America is the only continent where the levels of differentiation are similar for maternal and paternal lineages.     

Responses to cold shock in cyanobacteria

Acclimation of cyanobacteria to low temperatures involves induction of the expression of several families of genes. Fatty acid desaturases are responsible for maintaining the appropriate fluidity of membranes under stress conditions. RNA-binding proteins, which presumably act analogously to members of the bacterial Csp family of RNA chaperones, are involved in the maintenance of the translation under cold stress. The RNA helicase, whose expression is induced specifically by cold, might be responsible for modifying inappropriate secondary structures of RNAs induced by cold. The cold-inducible family of CIp proteins appears to be involved in the proper folding and processing of proteins. Although genes for cold-inducible proteins in cyanobacteria are heterogeneous, some common features of their untranslated regulatory regions suggest the existence of a common factor(s) that might participate in regulation of the expression of these genes under cold-stress conditions. Studies of the patterns of expression of cold-inducible genes in cyanobacteria have revealed the presence of a cold-sensing mechanism that is associated with their membrane lipids. Available information about cold-shock responses in cyanobacteria and molecular mechanisms of cold acclimation are reviewed in this article.     

Responses to heat and cold in lower mammals

A survey has been made of the literature pertaining to temperature regulation in the lower mammals.The following scheme represent a tentative outline of one probable evolutionary sequence of homeothermy: the first successful efforts to maintain a fairly uniform level of body temperature began on the psycho-physiological or behavioural level. The first directly physiological factor in the maintenance of homeothermy seems to have been a capacity for variation in metabolic heat production.The monotremes provides an example of a temperature regulation based solely on behaviour patterns and variation in heat production. The next factor to appear in the gradual development of refined homeothermy has been the regulation of physical heat exchange. A gradual improvement of such function is discernible along the phylum also correlated with increased thermal stress imposed by the environment. Regulation of physical heat exchange is first generally apparent in the marsupial order. The thermostatic arrangements responsible for efficient body temperature regulation have been developed gradually becoming increasingly complex and accurate. It is discussed how an efficient central nervous thermostatic control seems to have been the last factor developed to perfection in homeothermy.

---

Zusammenfassung übersichtsrefrat über die Temperaturregulation in niederen SÄugern. Das folgende Schema ist ein vorlÄufiger Entwurf über die wahrscheinliche Ausbildung der Homeothermie wÄhrend der Evolution:die ersten wirksamen Einrichtungen zur Erhaltung einer ziemlich uniformen Korpertemperatur waren psycho-physiologische Funktionen und Eigenarten im Verhalten. Die erste ausschliesslich physiologische Funktion zur Erhaltung der Homeothermie scheint die FÄhigkeit zur Änderung der WÄrmebildung im Stoffwechsel gewesen zu sein.Die Monotremata sind ein Beispiel für Temperaturregulation, die allein durch Verhaltensformen und Änderung der WÄrmebildung bestimmt wird. Der nÄchste Schritt wÄhrend der graduellen Entwicklung zur ausgebildeten Homeothermie war die Regulierung des physikalischen WÄrmeaustausches.Eine zunehmende Verbesserung dieser Funktionen ist in dem Stamm zu beobachten. Sie ist verbunden mit verstÄrkter Hitzebelastung durch die Umwelt.Die Regulierung des physikalischen WÄrmeaustausches ist bei den Marsupialia erstmalig nachweisbar.Die Einrichtungen für wirksame Körpertemperaturregulation haben sich langsam entwickelt und wurden immer komplexer und genauer. Die Körpertemperaturkontrolle durch das Zentralnervensystem scheint die letzte Einrichtung zur Vervollkommung der Homeothermie gewesen zu sein.

---

Résumé Ce travail passe en revue la régulation thermique des petits mammifères.Le schéma provisoire suivant indique les mécanismes possibles d'apparition de l'homéothermie pendant l'évolution: les premiers dispositifs efficaces maintenant une température corporelle à peu près constante étaient des fonctions psycho-physiologiques et des particularités du comportement. La première fonction purement physiologique contribuant à l'homéothermie semble avoir été la faculté de modifier la production de chaleur métabolique. Les monotrèmes sont un exemple de régulation thermique produite uniquement par des formes de comportement et par des changements de la production de chaleur. Le développement de l'homéothermie complète progressa ensuite par la régulation des échanges physiques de chaleur.Le perfectionnement de ces fonctions s'observe chez le phylum.Elle est liée à une surcharge de chaleur en provenance du milieu externe. La régulation des échanges physiques de chaleur est atteinte en premier par les marsupiaux. Les dispositifs efficaces de régulation de la température corporelle se sont développés lentement et sont devenus toujours plus précis et plus complexes. Le contrÔle de la température corporelle par le système nerveux central semble Être le dispositif le plus récent de l'homéothermie complète.

     

三种园林植物对夜间光照的响应与适应特征

光污染是城市生态系统中重要的污染类型,目前的研究集中在光污染对人类健康、昆虫生活史、生活习性、活动规律等方面,对植物生理生态的效应研究则较少。以凤仙花(Impatiens balsamina)、小叶栀子(Gardenia jasminoides)、夏菊(Dendranthema morifolium)为研究对象,研究白光LED灯从每天18:00—24:00照光(T1处理)、每天18:00—次日8:00照光(T2处理)以及自然光周期(CK)等3种光环境条件下,3种植物生物量积累与分配、开花特征、色素含量、碳氮含量及其比值(C/N比)、抗氧化酶等方面的响应与适应特征。结果表明,T1和T2处理增加了凤仙花的生物量(分别为CK的1.4和1.9倍),降低了叶片和茎的N含量,增加了叶片的C/N比(分别为CK的1.2和1.9倍),降低了叶片的色素含量;T1处理延迟了凤仙花的花期,T2处理条件下凤仙花不开花。T1和T2处理虽然没有影响小叶栀子的花期,但增加了花的数量,减小了花的平均重量,花的C/N比显著增加(T2处理为CK的1.3倍);T2处理降低了小叶栀子叶片的叶绿素a、b及总叶绿素含量,增加了丙二醛的含量(T2处理为CK的1.7倍)。夏菊的生物量及生理特征受到T1和T2处理的影响最小,但T1和T2处理均抑制了夏菊开花。这些结果表明凤仙花和夏菊开花对光污染引起光周期的变化比较敏感,凤仙花的生长和养分特征也受到夜间光照的显著影响,光污染对小叶栀子的叶片造成了显著伤害。总的来讲,与T2相比,T1处理对3种植物的负面影响较小,在城市照明的管理过程中,可以根据需要缩短夜间光照的时间,既可以节约能源,又可以减小对植物生理生态的负面影响。     

蠋蝽抗寒性对快速冷驯化的响应及其生理机制

快速冷驯化可以提高某些昆虫的耐寒性.为了探讨不同冷驯化诱导温度对蝎蝽抗寒性的影响及其生理机制,以室内人工饲养的第3代蝎蝽成虫为对象,利用热电偶、液相色谱分析等技术手段,测定了经15、10、4℃冷驯化4h和梯度降温(依次在15、10、4℃各驯化4h)冷驯化后,蠋蝽成虫过冷却点、虫体含水率及小分子碳水化合物、甘油和氨基酸含量,及其在不同暴露温度(0、-5、-10℃)下的耐寒性.结果表明:处理后暴露在-10℃时,梯度处理组和4℃冷驯化处理组的蝎蝽成虫存活率为58.3％,其他处理组及对照组(室温饲养)的存活率显著降低,平均为8.9％;梯度处理组与4℃冷驯化处理组蠋蝽成虫过冷却点平均为-15.6℃,比其他处理平均降低1.3℃;各处理虫体含水率无显著差异,平均为61.8％;与其他各组相比,梯度处理组和4℃冷驯化组蠋蝽成虫的葡萄糖、山梨醇和甘油含量分别增加2.82、2.65和3.49倍,丙氨酸和谷氨酸含量分别增加51.3％和80.2％,海藻糖、甘露糖和脯氨酸含量分别下降68.4％、52.2％和30.2％,而果糖含量各组间无显著差异.快速冷驯化对蠋蝽成虫具有临界诱导温度值,梯度降温驯化不能在快速冷驯化的基础上提高蠋蝽成虫的抗寒性.     

Responses of Quechua Indians to coca ingestion during cold exposure

Fourteen Quechua men chewed coca leaves as they were exposed to a mild cold stress of 15.5°C for two hours. When compared to their own responses in a similar exposure without coca, they showed lower finger and toe temperatures. This was attributed to a mild vasoconstriction induced by coca leaf chewing. During the second hour of cold, coca users also showed a more gradual decline in core temperature which could represent greater heat conservation.     

Population genetics of Dagestan highlanders

Subdivision of some isolates and heterogenic populations in Daghestan is analysed by human gene and phen frequencies. Comparative population study of phenotypic variability of quantitative characters (anthropometric, neurodynamic and psychodynamic) is carried out. Common hierarchy of variability for all populations as well as an effect of inbreeding and panmixis on variability of the above-mentioned quantitative characters in different populations is demonstrated.     

Local cold exposure of Andean Indians during normal and simulated activities.

Thermal resonses of Andean Indians were measured during several customary tasks associated with cold exposure in the highlands of southern Peru. These included surface temperature measurements of women while they washed clothing in the river and similar measurements of men while they constructed a diversion channel in the same river. A third test measured the effects of alcohol consumption on body temperatures during light activity. Women maintained slightly warmer hand than foot temperatures. Men maintained nearly equal hand and foot temperatures during the exposure period. Among male subjects the foot rewarmed at a faster rate than the hand. The results from the field studies compared favorably with results from earlier laboratory exposure tests. Comparisons between the river water exposure tests for males and females showed a consistent pattern where females maintained warmer hand and foot temperatures than males. These findings were in accord with previous laboratory studies among Quechua Indians and with the findings reported for other ethnic groups who experience natural cold stress. Alcohol ingestion appeared to have minimal effect in mitigating cold stress response during light activity. This finding was counter to earlier laboratory tests of resting subjects.     

Mitochondrial DNA analysis of ancient Peruvian highlanders

Ancient DNA recovered from 57 individuals excavated by Hiram Bingham at the rural communities of Paucarcancha, Patallacta, and Huata near the famed Inca royal estate and ritual site of Machu Picchu was analyzed by polymerase chain reaction, and the results were compared with ancient and modern DNA from various Central Andean areas to test their hypothesized indigenous highland origins. The control and coding regions of the mitochondrial DNA (mtDNA) of 35 individuals in this group were sequenced, and the haplogroups of each individual were determined. The frequency data for the haplogroups of these samples show clear proximity to those of modern Quechua and Aymara populations in the Peruvian and Bolivian highlands, and contrast with those of pre-Hispanic individuals of the north coast of Peru that we defined previously. Our study suggests a strong genetic affinity between sampled late pre-Hispanic individuals and modern Andean highlanders. A previous analysis of the Machu Picchu osteological collection suggests that the residents there were a mixed group of natives from various coastal and highland regions relocated by the Inca state for varied purposes. Overall, our study indicates that the sampled individuals from Paucarcancha and Patallacta were indigenous highlanders who provided supportive roles for nearby Machu Picchu.     

不同基因型水稻苗期抗氧化系统对低温胁迫的响应

以2个籼型水稻(Oryza sativa L. subsp. indica Kato)和2个粳型水稻(O. sativa L. subsp. japonica Kato)品种为材料,比较其幼苗经低温胁迫和恢复生长后的活性氧(ROS)代谢、抗氧化酶活性、抗氧化剂含量和渗透调节物质的变化。结果显示,经低温胁迫后,4个水稻品种的H_2O_2含量均显著升高;抗氧化酶系统中的5种酶活性均有不同程度升高,且超氧化物歧化酶(SOD)的活性增加显著,而谷胱甘肽还原酶(GR)的活性增加不显著。抗氧化剂还原型谷胱甘肽(GSH)和还原型抗坏血酸(AsA)在‘明恢86’中显著增加。渗透调节物质脯氨酸的含量在‘黔恢1385’和‘日本晴’中变化不显著;可溶性糖含量在‘明恢86’中变化不显著。经过7 d恢复生长后,4个水稻品种的上述各生理指标均不同程度恢复到处理前的水平。研究结果表明,抗氧化酶活性的升高有效降低了ROS的水平,缓解了低温冷害对细胞膜的伤害。低温胁迫时细胞内维持了较高的可溶性糖含量,提高了胞内水势,减少因细胞失水而对植物造成的伤害。     

Responses to lactation and cold exposure by deer mice (Peromyscus maniculatus)

Recently, much interest has been expressed in understanding how animals use phenotypic plasticity of tissue size and function to meet increased metabolic demands. We set out to learn (i) whether female deer mice (Peromyscus maniculatus) given lactation (two to seven pups per litter), cold (5 degrees C), or cold plus lactation as energy demands display phenotypic plasticity in organ size and function; (ii) whether that plasticity is similar to laboratory mice given the same demands; and (iii) whether lactational performance in deer mice is derived from limits on central or peripheral organs. We found that deer mice responded to lactation by increasing digestible food intake and increasing the masses of the stomach, small intestine, cecum and liver, and the length of the small intestine. Heart mass was lower in lactating than in nonlactating mice. Cold exposure also caused increases in digestible food intake and increases in the masses of the small intestine, kidney, and heart. We conclude that deer mice display organ tissue plasticity in response to both lactation and cold exposure in a similar manner to laboratory mice. We also conclude that deer mice are not limited by central processing organs because they are able to increase digestive organ size continuously with increased energetic demands.     

Adaptation to night shifts and synchronisation processes of night workers

Human beings are accustomed to being active and awake during the day, and asleep and rest at night. Since we live in a society which is organised predominantly along daytime activity, therefore working in the night shift may deeply disrupt our social and family life. It is also a well-known fact that night shift causes fatigue and circadian disruption. The basic manifestation of fatigue and circadian rhythm has been linked to health and safety problems, involving decrements in psychophysical and physiological functions, plus subjective complaints. In this context quantitative relationships between shift work and circadian rhythm need to be assessed to explore suitable time schedule, and to minimise sleep depth and fatigue. There is also a great need to discuss circadian disruption, sleepiness and the increasing cost of work related illness among night workers. In this regard, some aspects of fatigue and circadian disruption caused from night shift work are revealed in this paper aiming to increase workers' health, safety and well being as well as productivity. Light/dark cycle and social stimuli issues acting on the circadian timing systems are also explored to solicit opinions and discussion on the controversy of night work. Suggestions are therefore likewise given to enhance workers' adaptation to night shift and synchronization process.