Mating types in yeast,vomeronasal organ in rodents,homosexuality in humans: does a guiding thread exist?

Pheromones and their receptors are the molecules used by very different organisms in order to join two haploid cells. It happens evidently in yeast, since the two blending haploid cells are also the two mating organisms, whereas in rodents pheromone receptors are the triggers of the vomeronasal system which, supervising sexual behaviors, is responsible for copulation and therefore for fertilization. The debate is still open about the real significance of pheromones in humans but a working vomeronasal organ, able to recognize pheromones of the same sex, could be the simplest biological explanation of homosexuality. This hypothesis is discussed and connected with some well known experimental data.     

Biofeedback in medicine: who,when, why and how?

Biofeedback is a mind-body technique in which individuals learn how to modify their physiology for the purpose of improving physical, mental, emotional and spiritual health. Much like physical therapy, biofeedback training requires active participation on the part of patients and often regular practice between training sessions. Clinical biofeedback may be used to manage disease symptoms as well as to improve overall health and wellness through stress management training. Research has shown that biofeedback interventions are efficacious in treating a variety of medical conditions, and many Americans are turning to biofeedback and other less traditional therapies for their routine healthcare.Clinical biofeedback training is growing increasingly popular in the USA, as many people are seeking out relatively new approaches to healthcare. This article provides an overview of clinical biofeedback training, outlines two models of training, details research which has established how effective biofeedback is in patients with a given disease, and describes who should be referred for biofeedback training.     

K-selection, α-selection, effectiveness, and tolerance in competition: Density-dependent selection revisited

In the Drosophila literature, selection for faster development and selection for adapting to high density are often confounded, leading, for example, to the expectation that selection for faster development should also lead to higher competitive ability. At the same time, results from experimental studies on evolution at high density do not agree with many of the predictions from classical density-dependent selection theory. We put together a number of theoretical and empirical results from the literature, and some new experimental results on Drosophila populations successfully subjected to selection for faster development, to argue for a broader interpretation of density-dependent selection. We show that incorporating notions of alpha-selection, and the division of competitive ability into effectiveness and tolerance components, into the concept of density-dependent selection yields a formulation that allows for a better understanding of the empirical results. We also use this broader formulation to predict that selection for faster development in Drosophila should, in fact, lead to the correlated evolution of decreased competitive ability, even though it does lead to the evolution of greater efficiency and higher population growth rates at high density when in monotypic culture.     

Mortality differentials in Canada, 1951–1971: French,British, and Indians

Mortality differentials reflect in part the social and economic conditions of groups in society. In this paper, the relationship between ethnic origin and mortality is investigated from the point of view of convergence and minority group status hypotheses. Multivariate methods are used to study differences among the French, the British and Native Indian (includes Metis and Eskimos) populations of Canada over three census periods from 1951 to 1971. A significant downward trend in the death rates of all three subpopulations is noted, but substantial differences persist, as the pace of mortality decline over time varies across the three ethnic groups. In the twenty-year interval between 1951 and 1971, Native Indians have experienced spectacular reductions in their overall death rates, but in comparative terms, their mortality levels still exceed those of the French (who show intermediate levels) and the British ethnic groups. The multivariate analysis provides strong support for the minority status effect, which is taken to suggest that the roots of inequalities in survival probabilities are partly a result of social and economic disparities. The convergence thesis received some support: over time the general pattern is one of declining mortality with some narrowing of the differences. An examination of four broad causes of death (neoplasms, cardiovascular, accidents-violence, and "other") suggests that Native Indians are characteristic of populations undergoing epidemiologic and demographic transitions. Their elevated risk of accidents-violence reflects social disruption in the process of modernization. Causes of death of the French and British populations are characterized by higher risks of cancer and cardiovascular diseases, typical of advanced societies.     

Transition-state ensemble in enzyme catalysis: possibility, reality, or necessity?

Proteins are not rigid structures; they are dynamic entities, with numerous conformational isomers (substates). The dynamic nature of protein structures amplifies the structural variation of the transition state for chemical reactions performed by proteins. This suggests that utilizing a transition state ensemble to describe chemical reactions involving proteins may be a useful representation. Here we re-examine the nature of the transition state of protein chemical reactions (enzyme catalysis), considering both recent developments in chemical reaction theory (Marcus theory for SN2 reactions), and protein dynamics effects. The classical theory of chemical reactions relies on the assumption that a reaction must pass through an obligatory transition-state structure. The widely accepted view of enzymatic catalysis holds that there is tight binding of the substrate to the transition-state structure, lowering the activation energy. This picture, may, however, be oversimplified. The real meaning of a transition state is a surface, not a single saddle point on the potential energy surface. In a reaction with a "loose" transition-state structure, the entire transition-state region, rather than a single saddle point, contributes to reaction kinetics. Consequently, here we explore the validity of such a model, namely, the enzymatic modulation of the transition-state surface. We examine its utility in explaining enzyme catalysis. We analyse the possibility that instead of optimizing binding to a well-defined transition-state structure, enzymes are optimized by evolution to bind efficiently with a transition-state ensemble, with a broad range of activated conformations. For enzyme catalysis, the key issue is still transition state (ensemble) stabilization. The source of the catalytic power is the modulation of the transition state. However, our definition of the transition state is the entire transition-state surface rather just than a single well-defined structure. This view of the transition-state ensemble is consistent with the nature of the protein molecule, as embodied and depicted in the protein energy landscape of folding, and binding, funnels.     

New Delhi metallo-��-lactamase-1: local acquisition in Ontario, Canada, and challenges in detection

New Delhi metallo-β-lactamase-1 (NDM-1) is a recently identified metallo-β-lactamase that confers resistance to carbapenems and all other β-lactam antibiotics, with the exception of aztreonam. NDM-1 is also associated with resistance to many other classes of antibiotics. The enzyme was first identified in organisms isolated from a patient in Sweden who had previously received medical treatment in India, but it is now recognized as endemic throughout India and Pakistan and has spread worldwide. The gene encoding NDM-1 has been found predominantly in Escherichia coli and Klebsiella pneumoniae. We describe the isolation NDM-1–producing organisms from two patients in Toronto, Ontario. To the best of our knowledge, this is the first report of an organism producing NDM-1 that was locally acquired in Canada. We also discuss the evidence that NDM-1 can affect bacterial species other than E. coli and K. pneumoniae, the limited options for treatment and the difficulty laboratories face in detecting organisms that produce NDM-1.New Delhi metallo-β-lactamase-1 (NDM-1) is a metallo-β-lactamase that confers resistance to carbapenems and all other β-lactam antibiotics, with the exception of aztreonam. It is predominantly found in the Enterobacteriaeceae. It was first identified in Escherichia coli and Klebsiella pneumoniae isolated from a patient in Sweden who had previously received medical treatment in India. It is now recognized as endemic throughout India and Pakistan and has spread worldwide due to travel, “medical tourism” and the ability of the genetic element encoding the enzyme to transfer between bacteria.^1–3 Three reports of organisms producing NDM-1 in Canada have been published to date. In each instance, the organisms were isolated from the urinary tracts of patients who had recently been admitted to hospitals in India. Two of the isolates were strains of K. pneumoniae and one was a strain of E. coli.^4–6 Additional reports of isolation of organisms producing NDM-1 from patients in Canada have been presented in the lay press.Organisms that produce NDM-1 have been associated with resistance to classes of antibiotics other than the β-lactams, thus severely limiting options for treatment.² Infection control guidance regarding the management of colonization by or infection with organisms that produce carbapenemases, such as NDM-1, have recently been published by Canadian and European authorities.^7–9 An essential component of these recommendations is the rapid and accurate identification of the organisms in a clinical microbiology laboratory. The Clinical Laboratory Standards Institute (CLSI) and the United States Centers for Disease Control and Prevention (CDC) recommend screening for the production of carbapenemase using the Modified Hodge Test.^10,11 If the result of that test is positive, then the presence and type of carbapenemase can be confirmed by polymerase chain reaction.⁴Herein, we summarize two additional instances in which organisms producing NDM-1 were isolated from patients in Canada and the first where the organism appears to have been acquired in Canada.     

Minireview: The androgen receptor in breast tissues: growth inhibitor, tumor suppressor, oncogene?

Androgen receptor (AR) signaling exerts an antiestrogenic, growth-inhibitory influence in normal breast tissue, and this role may be sustained in estrogen receptor α (ERα)-positive luminal breast cancers. Conversely, AR signaling may promote growth of a subset of ERα-negative, AR-positive breast cancers with a molecular apocrine phenotype. Understanding the molecular mechanisms whereby androgens can elicit distinct gene expression programs and opposing proliferative responses in these two breast cancer phenotypes is critical to the development of new therapeutic strategies to target the AR in breast cancer.     

Radiotherapy facilities,equipment, and staffing in Poland: 2005–2011

Background and purpose

To evaluate the current status of radiotherapy facilities, staffing, and equipment, treatment and patients in Poland for the years 2005–2011 following implementation of the National Cancer Programme.

Methods

A survey was sent to the radiotherapy centres in Poland to collect data on available equipment, staffing, and treatments in the years 2005–2011.

Results

In 2011, 76,000 patients were treated with radiotherapy at 32 centres vs. 63,000 patients at 23 centres in 2005. Number of patients increased by 21%. In 2011, there were 453 radiation oncologists – specialists (1 in 168 patients), 325 medical physicists (1 in 215 patients), and 883 radiotherapy technicians (1 in 86 patients) vs. 320, 188, and 652, respectively, in 2005. The number of linear accelerators increased by 60%, from 70 units in 2005 to 112 in 2011. The current linac/patient ratio in Poland is 1 linac per 678 patients. Waiting times from diagnosis to the start of treatment has decreased.

Conclusion

Compared to 2005, there are more treatment facilities, more and better equipment (linacs), and more cancer care specialists. There are still large differences between the 16 Polish provinces in terms of equipment availability and ease of access to treatment. However, radiotherapy services in Poland have improved dramatically since the year 2005.     

α-ENaC in bullfrog embryo: expression in cement gland, gills and skin

The epithelial sodium channel (ENaC) is involved in Na⁺ responses such as Na⁺ absorption and salt taste. The alpha ENaC subunit (α-ENaC) is expressed in the skin of both the adult and larval (tadpole) bullfrog. α-ENaC expression in the developing bullfrog embryo has not been previously investigated. In this study, the expression of α-ENaC at various stages (Sts.) of bullfrog embryonic development is assessed by western blot and immunofluorescence analysis. Bullfrog α-ENaC (α-fENaC) protein was detected by western blot in embryos at Sts. (Gosner/Shumway) 19, 21 and 25. Immunofluorescence studies indicate that α-fENaC was localized to the embryonic cement glands at St. 18 (muscular response), St. 19 (heart beat) and St. 21 (mouth open and/or cornea transparent), to the external gills at St. 21 and to the outermost cell-layer of the skin at St. 25 (operculum complete). The function(s) of ENaC in these embryonic structures remain to be elucidated.     

FtsZ dynamics in bacterial division: What,how, and why?

Bacterial cell division is orchestrated by the divisome, a protein complex centered on the tubulin homolog FtsZ. FtsZ polymerizes into a dynamic ring that defines the division site, recruits downstream proteins, and directs peptidoglycan synthesis to drive constriction. Recent studies have documented treadmilling of FtsZ polymer clusters both in cells and in vitro. Emerging evidence suggests that FtsZ dynamics are regulated largely by intrinsic properties of FtsZ itself and by the membrane anchoring protein FtsA. Although FtsZ dynamics are broadly required for Z-ring assembly, their role(s) during constriction may vary among bacterial species. These recent advances set the stage for future studies to investigate how FtsZ dynamics are physically and/or functionally coupled to peptidoglycan metabolic enzymes to direct efficient division.     

Episodic memory in nonhumans: what, and where, is when?

Episodic memory is defined as the recollection of specific events in one's past, accompanied by the experience of having been there personally. This definition presents high hurdles to the investigation of episodic memory in nonhumans. Recent studies operationalize episodic memory as memory for when and where an event occurred, for the order in which events occurred, or for an animal's own behavior. None of these approaches has yet generalized across species, and each fails to capture features of human episodic memory. Nonetheless, the study of episodic memory in nonhumans seems less daunting than it did five years ago. To demonstrate a correspondence between human episodic memory and nonhuman memory, progress is needed in three areas. Putative episodic memories in nonhumans should be shown to be; first, represented in long-term memory, rather than short-term or working memory; second, explicit, or accessible to introspection; and third, distinct from semantic memory, or general knowledge about the world.     

Temporal variation in sex allocation in the mealybug Planococcus citri: adaptation, constraint, or both?

Sex ratio theory has been very successful in predicting under which circumstances parents should bias their investment towards a particular offspring sex. However, most examples of adaptive sex ratio bias come from species with well-defined mating systems and sex determining mechanisms, while in many other groups there is still an on-going debate about the adaptive nature of sex allocation. Here we study the sex allocation in the mealybug Planococcus citri, a species in which it is currently unclear how females adjust their sex ratio, even though experiments have shown support for facultative sex ratio adjustment. Previous work has shown that the sex ratio females produce changes over the oviposition period, with males being overproduced early and late in the laying sequence. Here we investigate this complex pattern further, examining both the robustness of the pattern and possible explanations for it. We first show that this sex allocation behaviour is indeed consistent across lines from three geographical regions. Second, we test whether females produce sons first in order to synchronize reproductive maturation of her offspring, although our data provide little evidence for this adaptive explanation. Finally we test the age at which females are able to mate successfully and show that females are able to mate and store sperm before adult eclosion. Whilst early-male production may still function in promoting protandry in mealybugs, we discuss whether mechanistic constraints limit how female allocate sex across their lifetime.     

Gorilla diet in the Lopé Reserve,Gabon:

Summary The results of an analysis of gorilla diet in the Lopé Reserve, Gabon are presented. Samples were assayed for nutrients and plant secondary compounds (total phenols, condensed tannins and alkaloids) in an attempt to explain gorilla food choice. The diet is the most diverse so far analysed for gorillas; it seems to be a balance between sugary fruit, proteinaceous leaves, and relatively fibrous stems. Most fruits and herbaceous stems are succulent, but some drier, fibrous fruit and bark is also consumed. Seeds are another component of the diet, including unripe ones. Fruit, seeds, leaves and bark may all contain very high levels of total phenols and condensed tannins; but all herbaceous stems assayed contain low levels of these compounds. Alkaloids are not apparently a significant component of gorilla foods, and may be avoided. Gorillas at Lopé tend to avoid fatty fruit, and select leaves which are high in protein and low in fibre compared to the general vegetation. When fruit and preferred young leaves are scarce, proteinaceous barks and mature leaves, and sugary pith, are important sources of nutrients. We conclude that gorillas exploit the broad frugivore niche in West African lowland forests, and are part of the frugivore community there. What distinguishes them is their ability to eat large fibrous fruit, mature leaves and stems, and to overcome high levels of phenolics (we use phenolics as an umbrella term for both total phenols and condensed tannins). Gorilla diet at Lopé overlaps greatly with that of sympatric, frugivorous, primates, and resembles more closely that of chimpanzees than it does gorilla diet studied elsewhere in Africa.