Relation between lung cancer,chronic bronchitis,and airways obstruction.

Since cigarette smoking is an important cause of lung cancer and chronic bronchitis both conditions should occur together more often in cigarette smokers than would result from chance. If they do commonly occur together then severe airways obstruction, which is often associated with chronic bronchitis, should also be often associated with lung cancer. To discover whether this were so three groups of patients were studied at the London Chest Hospital. Two hundred men and 43 women who presented with lung cancer provided information on the prevalence of defined chronic bronchitis and airways obstruction in those suffering from lung cancer. The third group consisted of 233 men presenting with defined chronic bronchitis who were kept under observation to discover how many would die from lung cancer. The results suggested that simple bronchitis and lung cancer often occur together but that obstructive bronchitis and lung cancer do not often occur together. The lack of association between lung cancer and severe airways obstruction requires an explanation.     

Selection-induced mutations.

Some spontaneous mutations are specifically 'adaptive' in two ways: in that they occur more often when they are useful than when they are irrelevant to the survival of the cell; and in that they occur as specific responses to selective pressures. These 'selection-induced mutations' occur both in bacteria and in the eukaryotic microorganism, yeast.     

被子植物地下结实和地上/下两型结实的生态适应意义

地下结实和地上/下两型结实是被子植物两类独特的结实方式, 多发生在陆生和草本植物中, 主要生长在缺少水分或光照、土壤扰动频繁及环境波动较为剧烈的生境中。两种结实方式不仅是植物适应性进化的重要方面, 也是选择性进化的产物。其中, 地下结实对于植物在母株附近适宜微环境中保存后代、在极端环境下保持种子活力、逃避地面动物取食和火灾伤害以及延长果实发育时间等方面, 地上/下两型结实对于减少同胞子代及种群内竞争、维持和扩大种群以及提高物种的适应力和进化可塑性等方面, 都具有重要的生态适应意义, 是植物抵御不利生物与非生物环境的两类重要防御策略。但两种结实方式同时也存在着限制果实与种子扩散、影响基因传递与种群遗传结构、加大种群隔离以及提高繁殖代价等进化限制, 对物种的分布、种群增长、迁移、适合度和生活史进化等具有重要影响。目前, 地下和地上/下两型结实现象分别在大约24科57属和13科34属中进行了报道, 其中在菊科、十字花科、豆科和玄参科等类群中两种结实现象同时存在。从系统发育看, 地下结实在木兰分支、单子叶植物分支及双子叶植物分支中均存在, 而地上/下两型结实仅出现在单子叶植物分支和双子叶植物分支中, 在被子植物基部类群(ANITA类群)中两种结实方式均不存在。该文对植物地下和地上/下两型结实的类型、系统进化、繁殖特性和扩散对策进行了介绍, 并对其生态适应意义进行了总结, 以期为深入研究植物结实的进化策略提供参考。     

Intracisternal tubules and intramitochondrial filaments in cells of a snail, Limnaea

Epithelial and peritubular cells associated with the reproductive tract of the snail, Limnaea stagnalis, contain an extensive system of endoplasmic reticulum that is often dilated with many closely packed intracisternal tubules. The intracisternal tubules are approximately 24-28 nm in diameter and they are often hexagonally packed. They have a two-layered wall, possess fine interconnections, and extend linearly for considerable distances, but angular bends in the tubules also occur. Mitochondria in the peritubular cells contain solid, filamentous structures 9-12 nm in diameter and triangular-shaped structures when sectioned in the mitochondrial matrix.     

The autumn and spring emigrations of juvenile Atlantic salmon, Salmo salar L., from the Girnock Burn, Aberdeenshire, Scotland: environmental release of migration

Peaks in the emigratory activity of sexually immature, juvenile Atlantic salmon, Salmo salar , occur in autumn and early winter and in spring at the Girnock Burn in Aberdeenshire. Stream temperature is apparently without effect on the release of potentially emigrant fish from the stream. Migrants tend to leave the stream when stream discharge rate is elevated. Whereas downstream movements in autumn and the earlier part of the spring are made almost invariably when the stream's discharge rate is higher than the seasonal norm, later in spring they often occur when discharge rates are lower than the seasonal norm and when no apparent increase in absolute stream discharge rate has occurred. Emigration is depressed in the lunar quarter centred on the full moon. The nature of the relationship between the autumn and spring emigrations is discussed.     

Salmonella typhimurium enterotoxin epitopes shared among bacteria

Abstract Selection-induced mutations (SIMS) are mutations that occur as specific and direct responses to environmental challenges, and that occur more often when they are selectively advantageous than when they are selectively neutral. This review includes discussions of how the occurrence of SIMS is measured, acquisitive evolution by SIMS, some of the controversies surrounding SIMS and models that have been advanced to explain the specificity of SIMS, and the requirement of a functional recA gene product for SIMS to occur.     

Predation, sex ratios, and male competition in equids (Mammalia: Perissodactyla)

Existing data indicate that a greater preponderance of adult females rather than adult males occurs in most species of mammals. The hypothesis that such differences arise as a result of intermale reproductive competition for females (and not predation) was examined in the Equidae by comparing populations of horses ( Equus caballus ), asses ( E. asinus ), and two species of zebras ( E. zebra and E. burchelli) in predator-free, predator-rich and insular ecosystems.
Evidence is presented that: (1) sex differences in adult mortality occur; (2) they relate to the type and intensity of natural predation; and (3) asymmetries in sex ratios are most often explicable in terms of intermale reproductive competition. Exceptions are discussed and they are complicated by numerous proximate factors.     

Desert Truffles of the African Kalahari: Ecology,Ethnomycology, and Taxonomy

Desert Truffles of the African Kalahari: Ecology, Ethnomycology, and Taxonomy. The Khoisan people of the Kalahari Desert have used truffles for centuries. The extreme conditions in which desert truffles grow means that they fruit only sporadically when adequate and properly distributed rainfall occurs, and then only where suitable soil and mycorrhizal hosts occur. Truffles are hunted in the Kalahari by men and women; they look for cracks in the soil, often humped, caused by expansion of the truffles, which are then extracted with hands or digging sticks. The truffles are eaten raw or cooked (boiled, roasted over fire, or buried in hot ashes). Commercial harvest of Kalahari truffles has increased in the last decade and the quantities harvested have been observed to be declining where livestock have been concentrated.     

Phase response curves for social entrainment

Summary Phase shifts in free-running activity rhythms of male golden hamsters,Mesocricetus auratus, often occur when they establish a new territory and home after a cage change. Similar shifts also often occur after pairs of animals interact with each other for half an hour. When these events take place during the middle of the hamsters' subjective day, they produce phase advances: when late in the subjective night, they produce phase delays. Repeated social interactions at the same time of day can entrain activity rhythms in a way consistent with the shape of the phase response curves. Not all individuals become entrained, as is predictable from the modest amplitude of the phase response curve. The effects of social interactions and of other disturbances may be mediated through an oscillator phased by general arousal. The present findings have implications for the interpretation of drug-induced changes in biological rhythms.     

Method for Assigning Categorical Rank in Female <Emphasis Type="Italic">Pan troglodytes schweinfurthii</Emphasis> via the Frequency of Approaches

Establishing the order of a dominance hierarchy among female chimpanzees (Pan troglodytes) is complicated by the fact that they often forage solitarily, and aggressive interactions between them occur infrequently. Authors of previous studies have typically ranked females via the direction of submissive pant-grunts and the outcome of agonistic interactions. Given that higher rank correlates with higher reproductive success in female chimpanzees, assessing rank is important but may be limited by sparsely populated dominance matrices. I tested the hypothesis that rank predicts the direction of female approaches. There is a significant relationship among Gombe females between the frequency with which a female was approached and her dominance rank. Dominant females approached other females less often than they were approached. Though approached frequencies failed to meet the criteria for formal rank indicators, they may be useful as real indicators of subordination. Because approach interactions occur far more frequently than pant-grunts, they may be useful in assigning categorical rank when traditional dominance metrics are limited.     

Relationships betweenParacaryum intermedium andP. boissieri on Sinai,and the generic separation ofParacaryum andMattiastrum (Boraginaceae)

Paracaryum intermedium andP. boissieri differ only in their inflexed or flattened fruit wings, and often occur in mixed populations on Mt. Katherina, Sinai. This and cultivation experiments suggest that they may represent forms of a single species only. The fruit characters mentioned therefore are hardly useful for a generic separation ofParacaryum andMattiastrum.     

Refractive spherules in phloem ofMicrosorium scolopendria andPsilotum nudum

Summary Phloem tissues ofMicrosorium scolopendria (Polypodiaceae) andPsilotum nudum (Psilotaceae) were examined with light and electron microscopes. The characteristic refractive spherules in the sieve elements ofM. scolopendria apparently develop from endoplasmic reticulum-derived cytoplasmic vesicles. In both taxa they have not been observed to be spatially related to plastids or mitochondria. Refractive spherules contain protein and often occur in the peripheral cytoplasm of mature sieve elements. InM. scolopendria they also occur in pericycle cells. Significant differences in refractive spherule substructure occur between the two taxa studied.     

Influence of Chimpanzee Predation on Associations Between Red Colobus and Red-tailed Monkeys at Ngogo,Kibale National Park,Uganda

Colobines often associate with cercopithecines at various African sites. Such polyspecific associations presumably have an antipredation function. At Ngogo, Kibale National Park, Uganda, red colobus (Procolobus rufomitratus) spend considerable time in association with red-tailed monkeys (Cercopithecus ascanius), and they are also heavily hunted by chimpanzees (Pan troglodytes). I conducted behavioral observations and playback experiments to test the hypothesis that red colobus and red-tailed monkeys obtain mutual protection and predator-related benefits by associating. Despite high chimpanzee hunting pressure on red colobus and much lower hunting pressure on red-tailed monkeys, red-tailed monkeys initiate, maintain, and terminate the associations. The results suggest that rather than providing red colobus with protection against chimpanzees, the associations occur mostly because they protect red-tailed monkeys against predation by eagles.     

Agonistic aiding: Kinship,rank, age,and sex influences

An analysis of 3,774 episodes of agonistic aiding collected during a two-year study of a rhesus monkey group (Macaca, mulatta) indicated the differential influence of kinship and rank relationships on the participation of different age-sex classes in both aid to victims and aid to aggressors. Most aiding favored victims rather than aggressors and was much more likely to occur when matrilineal kin were involved. Females were more likely to aid than were males, and the frequency of their participation increased with age. Females were much more influenced by kinship than were males and defended or aggressively supported kin against any third party regardless of dominance relationships. Adult males seldom aided against animals that were dominant to themselves; the rare exceptions occurred when adult males defended kin. Aiding was far more likely to occur if the victim was squealing, and noisy agonistic episodes often involved multiple aiders on both sides. Aiding patterns had some potential to insure dominance rank inheritance within families, in accordance with the Kawamura hypothesis. In aiding animals outside of their own matrilines, however, group members aided randomly with respect to this model. There was little evidence that aiding functioned to support individuals when they targeted animals to which they should be dominant as adults based on matrilineal dominance relationships. Most defensive aiding seemed to function primarily to defend victims (primarily kin) of aggression. Aggressive support of the attacker, on the other hand, seemed to function primarily to reinforce coalitions with the attacker. The identity of the victim was unimportant as long as it was neither kin to nor dominant to the aider. Aggressive support of attackers did not overturn existing dominance relationships.     

A clarification of two congeners,Pseudodiaptomus lobipes and P. binghami (Calanoida,Pseudodiaptomidae) from India,with description of P. mixtus sp.n. from Bangladesh

Two closely related and often confused species of Pseudodiaptomus from the Lobus-species group, P. lobipes and P. binghami are redescribed from various locations along the east coast of India. These species predominately occur in freshwater though they can survive temporary periods of increased salinity. The distinctive features of the species are found on: female caudal ramal setae, female and male urosome 1–2 spinulation patterns, and fifth legs. A new species P. mixtus from Bangladesh is described.     

Laughing,Smiling, and Talking: Relation to Sleeping and Social Context in Humans

The propabilities of laughing, smiling, or talking during a given hour and in various social environments were investigated by having undergraduate college students record their performance of these activitics in a log book during a one-week period. All three activities were least likely to occur during the hours immediately before bedtime and after waking and were most frequent in social situations. Smiles and laughs, like talking, were performed primarily during social encounters and were often part of verbal and nonverbal conversations. Because laughing and smiling are phasic social acts, they are of limited value as indices of ongoing (tonic) emotional state. The role of laughing, smiling, and talking in communication, the production of mood, and social bonding is considered.     

Parent choice by larval convict cichlids,Cichlasoma nigrofasciatum (Cichlidae,Pisces)

Fourteen pairs of convict cichlids, Cichlasoma nigrofasciatum (‘gold’ and wild type) were bred a total of 21 times. Both parents tended their young together under two treatments: (1) in the presence of predators of fry and (2) not in the presence of predators of fry. When the young were free-swimming for 2 days they were tested in groups of 31 to determine which parent they preferred. Whether a preference was exhibited, the sex of the parent chosen, and the latency to choice were recorded. No difference in wild-type versus gold parents and offspring was detected. Most groups of young made a choice. Although maternal preference was indicated most often, paternal choices did occur. The amount of time the young were separated from the parents before testing was found to be important and affected whether or not a choice was made under the two rearing conditions. Latency to choice was shorter for groups of young raised with predators.     

Ovarian dysfunction, stress, and disease: a primate continuum

Menopause is recognized as a period of increased risk for coronary heart disease (CHD) and osteoporosis. Vulnerability to these conditions is often attributed to the naturally occurring estrogen deficiency characteristic of this part of the life cycle. Premenopausal reductions in endogenous estrogen occasioned by functional ovarian abnormalities or failure are hypothesized to be similarly pathogenic and to accelerate development of CHD and osteoporosis prematurely, thereby increasing the health burden of older women. These functional abnormalities, which occur along a continuum from mild, luteal phase progesterone deficiency to amenorrhea, are relatively common and are often attributed to psychogenic factors (stress, anxiety, depression, or other emotional disturbance), exercise, or energy imbalance. Although numerous investigators have commented on these functional deficits, the abnormalities can be difficult to diagnose and are generally unappreciated for the contribution they may make to postmenopausal disease. Studies in nonhuman primates confirm that these deficits are easily induced by psychological stress and exercise, and that they accelerate the development of cardiovascular disease and perhaps bone loss in the presence of a typical North American diet. However, functional reproductive deficits are also reversible and are thus potentially amenable to environmental or behavioral intervention. Data from both women and nonhuman primates support the hypothesis that functional reproductive deficits are adaptive when triggered appropriately but are detrimental when activated in an environment (e.g., sedentary lifestyle, high-fat diet) permissive to the development of chronic disease.     

Optimal foraging, specialization, and a solution to Liem's paradox

Species that appear highly specialized on the basis of their phenotype (e.g., morphology, behavior, and physiology) also sometimes act as ecological generalists. This apparent paradox has been used to argue against the importance of competition as a diversifying evolutionary force. We provide an alternative explanation based on optimal foraging theory. Some resources are intrinsically easy to use and are widely preferred, while others require specialized phenotypic traits on the part of the consumer. This asymmetry allows optimally foraging consumers to evolve phenotypic specializations on nonpreferred resources without greatly compromising their ability to use preferred resources. The evolution of phenotypic specialization on nonpreferred resources can be driven by competition, but the specialists act as ecological generalists whenever their preferred resources are available. Our model identifies at least three different concepts of specialization that need to be distinguished, based on diet, prey utilization efficiencies, and phenotypic adaptations. The relationships among these concepts are complex and often counterintuitive. Specialists should often reject the very resources that they have evolved traits to use. The most extreme phenotypic specializations should occur in the absence of a trade-off between using preferred and nonpreferred resources. Our model may explain why extreme phenotypic-specializations evolve more often in fish communities than in terrestrial vertebrate communities and provides a mechanism whereby species can coexist in stable communities despite common preferences for some resources.     

Bordered pits in ray cells and axial parenchyma: the histology of conduction, storage, and strength in living wood cells

Bordered pits occur in walls of living ray cells of numerous species of woody dicotyledons. The occurrence of this feature has been minimally reported because the pits are relatively small and not easily observed in face view. Bordered pits are illustrated in sectional view with light microscopy and with scanning electron microscopy in face view for dicotyledonous and gnetalean woods. Bordered pits are more numerous and often have prominent borders on tangential walls of procumbent ray cells, but also occur on radial walls; they are approximately equally abundant on tangential and horizontal walls of upright cells, suggesting parallels to cell shape in flow pathway design. Axial parenchyma typically has secondary walls thinner than those of ray cells, but bordered pits or large simple pit areas occur on some cross walls of parenchyma strands. There is no apparent correlation between the phylogenetic position of species and the presence of borders in ray cells or axial parenchyma. Bordered pits represent a compromise between maximal mechanical strength and maximal conductive capability. High rates of flow of sugar solutions may occur if starch in ray cells or axial parenchyma is mobilized for sudden osmotic enhancement of the conductive stream or for rapid development of foliage, flowers, or fruits. Measurement of the secondary wall thickness of ray cells may offer simple inferential information about the role that rays play in the mechanical strength of woods. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 157–168.