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.     

The case for studying tadpole autecology,with comments on strategies to study other small,fast-moving animals in nature

Two of the most fundamental questions in tadpole biology, also applicable to most small, under-studied organisms are: (1) ‘Why are they built the way they are?’ and (2) ‘Why do they live where they do?’ Regrettably, despite significant progress in most aspects of tadpole biology, the answers to these questions are not much better now than they were in the last century. We propose that an autecological approach, that is the careful observation of individuals and how they interact with the environment, is a potential path towards a fuller understanding of tadpole ecomorphology and evolution. We also discuss why more attention should be given to studying atypical tadpoles from atypical environments, such as torrential streams, water-filled cavities of terrestrial plants and wet rock surfaces neighbouring streams. Granted, tadpoles are rare in these settings, but in those unusual habitats the physical environments can be well described and characterized. In contrast, the more common ponds where tadpoles are found are typically too structurally complex to be easily delineated. This makes it difficult to know exactly what individual tadpoles are doing and what environmental parameters they are responding to. Our overall thesis is that to understand tadpoles we must see exactly what they are doing, where they are doing it, and how they are doing it. This takes work, but we suggest it is feasible and could greatly advance our understanding of how anuran larvae have evolved. The same strategies for studying tadpoles that we encourage here can be applied to the study of many other small and fast-moving animals.     

Mouse osteoblasts synthesize collagenase in response to bone resorbing agents

Bone cells isolated from mouse calvariae by a sequential digestion procedure have many osteoblast characteristics: they respond to PTH and prostaglandin E2 by activation of adenylate cyclase but not to calcitonin, they stain for alkaline phosphatase and they make only type I collagen. In confluent monolayer culture, they do not secrete collagenase in appreciable quantities, unless stimulated with resorptive substances such as PTH, prostaglandin E2, 1,25(OH)2 vitamin D-3 and monocyte-conditioned medium. This suggests they play a direct role in bone resorption.     

The natural history of visiting: responses to Charles Waterton and Walton Hall

Natural history collections are typically studied in terms of how they were formed rather than how they were received. This gives us only half the picture. Visiting accounts can increase our historical understanding of collections because they can tell us how people in the past understood them. This essay examines the responses of visitors to Walton Hall in West Yorkshire, home of the traveller-naturalist Charles Waterton and his famous taxidermic collection. Waterton’s specimens were not interpreted in isolation. Firstly, they were experienced as components of a larger visiting experience, in which travelling to the Hall, being admitted to the grounds, viewing the park, and meeting the owner, were all just as significant as seeing the specimens themselves. Secondly, they were interpreted in conjunction with familiar stories and images relating to Waterton’s adventurous collecting activities. Visiting accounts can help us begin to recover what people thought about Waterton and his collection in the nineteenth century. Furthermore, in so far as they were responsible for a large part of his subsequent reputation, they can help us better understand our own, present-day conceptions of Charles Waterton and Walton Hall.     

Dependence receptors: Mechanisms of an announced death

Dependence receptors form a family of functionally related receptors which are all able to induce two completely opposite intracellular signals depending on the availability of their ligand. Indeed, in its presence, they mediate a positive, classical signal transduction of survival, differentiation or migration but without it, they trigger a negative signal which leads to cell death. The molecular mechanisms involved in triggering cell death in the absence of ligand are starting to be unravelled: dependence receptors are recruited at well-defined domains at the plasma membrane, they trigger cell death through a monomeric form, they are cleaved by caspases and they recruit a caspase activating complex.     

Appointment systems: evaluation of a flexible system offering patients limited choice

To test the efficiency of a flexible appointments system patients seeing one of the partners in a semirural dispensing practice were asked to choose whether they wanted appointments lasting five, 10, or 15 minutes. After seeing the doctor they were asked to fill in a questionnaire that asked, among other questions, how long an appointment they had booked, whether they had felt rushed, whether the doctor had seemed hurried, whether they had seen the doctor on the day they wanted, how long they had had to wait in the surgery, and whether they liked the system. Five minute appointments had been chosen by 124 of the 309 patients who returned completed questionnaires, 10 minute appointments by 155, and 15 minute appointments by 30. Mean consultation times were 6·1, 9·2, and 12·9 minutes, respectively. Altogether 298 patients liked the system.An appointment system that was flexible while remaining practical and efficient resulted from letting patients choose the length of their appointment. Such a system encourages patients to share in the responsibility of organising a practice efficiently.     

Responses of Hebeloma radicosum fruit-bodies to light and gravity: negatively gravitropic and nonphototropic growth

Responses of the long-rooting agaric Hebeloma radicosum fruit-bodies to light and gravity were studied. In light from below or obliquely below, fruit-bodies grew straight downward with gills tilted and cap swollen and waved if they had emerged downward from the culture medium, or bent upward from the beginning if they had emerged obliquely downward. In light from above or obliquely above, they grew upward if they had emerged upward. Thus, they did not grow toward unilateral light from obliquely below or obliquely above, and hence their growth was nonphototropic and negatively gravitropic from the beginning of development. Even the straight downward growth seems to be latently negative-gravitropic. In the dark, fruit-bodies grew upward, forming pseudorhizas, but they remained immature; they matured only in the light. These characteristics may be related to the growth habits of the fungus colonizing deep in the ground, forming primordia there, and developing mature fruit-bodies on the ground. Received: March 26, 2001 / Accepted: July 12, 2001     

河南小秦岭自然保护区蕨类植物区系研究

小秦岭自然保护区共计有蕨类植物23科46属107种.其区系基本特征是:地理成分多样,区系联系广泛并具有一定的古老性;以温带性质为主,但有较明显的热带残遗性和亲缘性;特有现象明显,是东亚成分分布中心的一部分;隶属于华北区系,兼有强烈的西北和西南区系特色.     

Doin' what comes natur'lly

Behavior affects evolution in many ways. Organisms are adapted for what they do, but they also do what they are adapted for.     

Five-Year Olds,but Not Chimpanzees,Attempt to Manage Their Reputations

Virtually all theories of the evolution of cooperation require that cooperators find ways to interact with one another selectively, to the exclusion of cheaters. This means that individuals must make reputational judgments about others as cooperators, based on either direct or indirect evidence. Humans, and possibly other species, add another component to the process: they know that they are being judged by others, and so they adjust their behavior in order to affect those judgments – so-called impression management. Here, we show for the first time that already preschool children engage in such behavior. In an experimental study, 5-year-old human children share more and steal less when they are being watched by a peer than when they are alone. In contrast, chimpanzees behave the same whether they are being watched by a groupmate or not. This species difference suggests that humans'' concern for their own self-reputation, and their tendency to manage the impression they are making on others, may be unique to humans among primates.     

The consultation and the therapeutic illusion.

At 45 general-practice surgery sessions 200 patients in whom no definite diagnosis could be made were randomly selected for one of two procedures. Either they were given a symptomatic diagnosis and medications, or they were told that they had no evidence of disease and therefore they required no treatment. No difference in outcome was found between these two methods as judged by the return or not of the patient within one month and his statement that he did or did not get better.     

The control of nest depth in a digger wasp (Sphex ichneumoneus L.)

Golden digger wasps, Sphex ichneumoneus L. (Sphecidae), are a solitary, ground-nesting species that dig burrows to particular depths in the soil. I develop and evaluate alternative hypeses about the mechanisms controlling digging behaviour. By altering the wasps' burrows as thare digging, I show that they are not digging for some prescribed length of time nor are they diggingtil they reach some suitable environmental characteristic deep in the soil. Rather, they appear be digging until they reach a particular tunnel length, making corrections if the tunnel is too shallor too deep. This distance can be altered somewhat by surface environmental conditions.     

Aestivo-hibernal reproductive diapause in Drosophila moriwakii: flight as a controlling factor

Drosophila moriwakii Okada & Kurokawa (Diptera; Drosophilidae) generally has only one generation per year and enters aestivo-hibernal reproductive diapause in Sapporo, northern Japan, but a small fraction of the population produced a second generation in summer at a place where breeding resources were abundant. In this species, diapause seems to be controlled by flight activity. When flies were cultured in cages in which they were able to fly freely, they entered diapause irrespective of photoperiod, but they did not do so at long daylengths when cultured in small vials in which they were prevented from flying. Furthermore, flies with wings removed did not enter diapause at long daylengths even if they were cultured in the cages.     

Interdisciplinary assessment of adherence to guidelines: a bold step

Guidelines from professional societies have acquired a prominent position in medicine. Conceived with the purpose of assisting clinicians in daily decision-making, they now delineate entitlements of patients, including reimbursements, they provide a basis for professional audits and, not the least important, they provide a framework for legal procedures.     

The uses of racism: whitewashing new Europeans in the UK

In many respects, recent East European migrants in the UK look like past migrants to the UK: they left poorer parts of the world in search of work and the better life in the UK. But in other respects, they look different: they are white. Their putative whiteness, however, has not exempted them from the effects of racism. But while there is growing evidence of how they have been targets of racism, less attention has been focused on how they are also perpetrators of racism. The purpose of this paper is to compare the ways Hungarians and Romanians wield ‘race’ to assert and defend the relatively privileged position their putative whiteness affords them in the UK's segmented labour market. I argue that these migrants mark, evaluate and rank difference in racialized ways to secure both social-psychological and material benefits.     

The Development of Play in Preschoolers

The motives of play activity constitute a key question. It is no accident that views on play diverge most conspicuously with regard to the the stimuli leading to play. Theories of satisfaction, pleasure, internal primary drives and self-affirmation—all "in-depth theories"—are essentially theories of the motivating forces that give rise to play. The principal flaw in these conceptions is how they construe the motivating forces of play: they are situated in the subject, in the child and in the child's experiences. These theories discount the fact that these experiences are but secondary to an activity, i.e., they are symptomatic in that they indicate the activity is indeed taking place, but they tell us nothing about the real, objective, stimuli of the activity.     

Nest-site selection in the great golden digger wasp, Sphex ichneumoneus L. (Sphecidae)

Abstract. 1. Sphex ichneumoneus are solitary, ground-nesting wasps with apparently broad nesting requirements.
2. Nest-site selecting behaviour involves four levels of decisions. First, the wasps are not active unless temperatures are high and they are less active during cloudy weather. Second, at the beginning of a nesting sequence they generally fly to the site from which they emerged, but occasionally they fly to other flat, vegetation-free areas. Third, after landing, they engage in a predigging search of the area, walking around, looking into and briefly digging in the nests of other wasps. In this way they apparently compare and choose to begin digging in the warmest areas available which are not too close to other nests. Fourth, if the soil is too soft and collapses or if it is too hard-packed, the wasp resumes the predigging search. The preference for digging within a range of compactness means that they generally choose sandy loam.
3. Theory would suggest that the wasps may spend an optimal amount of time in the predigging search behaviour and that frequency-dependent selection may be an important factor in the choice of nesting sites.
4. By choosing nesting sites according to these rules, the wasps are ensuring that their offspring develop in the warmest and best-drained soils available.     

Reactions to children's faces: Resemblance affects males more than females

Since cuckoldry risk is asymmetrical, we hypothesized that parental investment would be more affected by paternal than maternal resemblance. To test this hypothesis, we asked subjects hypothetical questions about investing in children under conditions in which their faces or those of other people had been morphed with photographs of children. Males were more likely to choose a face they had been morphed with as the most attractive, the child they were most likely to adopt, the child they would like to spend the most time with, the child they would spend US$50 on, and the child they would least resent having to pay child support for. Reactions to children's faces by females were much less affected by resemblance.     

Significance of family photographs for genetic counseling in sex-linked heredity

Authors remember the interest of the old photographs belonging to the families; the authors show how they can help the diagnosis; they can also help to assert the mode of inheritance; in few cases, they can find some female carriers with clinical signs; at last, infrequently, they prove the presence of the disease in a remote generation: so, they prove that the one case is not sporadic but is a familial case; this fact is very important for the genetic counselling of the females of this family. With some cases of the genetic counselling unit of Rennes, authors explain these various situations.     

Development of path stereotypy in a single day in rats on a multiple-T maze

Humans and animals trained on sequential reaction tasks show decreases in reaction time and increases in anticipatory movements even long after they have ceased to make errors. Humans show these changes even when they do not explicitly recognize that they performed a repeating sequence. We have developed a task which rats learn to perform error-free quickly, but in which they continue to show path-refinement on a single day. This task may enable the study of performance strategy changes occurring within a single day.