Showing off,handicap signaling,and the evolution of men's work

Zahavi's 1 , 2 handicap principle makes “waste” a common outcome of signal selection because the cost of a signal guarantees its honesty. The capacity to bear the cost reveals the show‐off's hidden qualities. While displays take many forms, some also provide fitness‐related benefits to the audience in addition to information about the show‐off. Zahavi 3 has used the handicap principle to explain both merely wasteful displays and altruistic behavior. Here we focus on the distinction between these two kinds of display and the importance of benefits other than information in show‐off explanations of a particular puzzle in human evolution: men's work. Males of other primate species do not contribute any significant fraction of the food consumed by females and juveniles. Our own species is different. When people live on wild foods, hunting is usually a specialty of men, and meat is commonly a substantial component of everyone's diet. Here we explore the hypothesis that this unique male subsistence contribution may have evolved as hunting large animals became a focus of competitive display.     

Pathogenesis of HIV infection: what the virus spares is as important as what it destroys

Upon transmission to a new host, HIV targets CCR5+ CD4+ effector memory T cells, resulting in acute, massive depletion of these cells from mucosal effector sites. This depletion does not initially compromise the regenerative capacity of the immune system because naive and most central memory T cells are spared. Here, we discuss evidence suggesting that frequent activation of these spared cells during the chronic phase of HIV infection supplies mucosal tissues with short-lived CCR5+ CD4+ effector cells that prevent life-threatening infections. This immune activation also facilitates continued viral replication, but infection and killing of target T cells by HIV are selective and the impact on effector-cell lifespan is limited. We propose, however, that persistent activation progressively disrupts the functional organization of the immune system, reducing its regenerative capacity and facilitating viral evolution that leads to loss of the exquisite target cell-sparing selectivity of viral replication, ultimately resulting in AIDS.     

Polydomy in ants: what we know, what we think we know, and what remains to be done

The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 319–348.     

Physiological responses to acute experimental hypoxia in the air-breathing Indian catfish, Clarias batrachus (Linnaeus, 1758)

With an aim to study the mechanism of adaptation to acute hypoxic periods by hypoxia-tolerant catfish, Clarias batrachus, the mass-specific metabolic rate (VO₂) along with its hematological parameters, metabolic response and antioxidant enzyme activities were studied. During progressive hypoxia, C. batrachus was found to be an oxyconformer and showed a steady decline in its aquatic oxygen consumption rate. When C. batrachus was exposed for different periods at experimental hypoxia level (0.98?±?0.1 mg/L, DO), hemoglobin and hematocrit concentrations were increased, along with decrease in mean cellular hemoglobin concentration, which reflected a physiological adaptation to enhance oxygen transport capacity. Significant increase in serum glucose and lactate concentration as well as lactate dehydrogenase activity was observed. Antioxidant enzymes were found to operate independently of one another, while total glutathione concentration was unaffected in any of the tissues across treatments. These observations suggested that hypoxia resulted in the development of oxidative stress and C. batrachus was able to respond through increase in the oxygen carrying capacity, metabolic depression and efficient antioxidant defense system to survive periods of acute hypoxia.     

Skin temperature and lactate threshold during muscle work in sportsmen

The purpose of the investigation was to estimate change of a thermal condition of an organism during exhausting work (maximal aerobic test) on cycle ergometer on the basis of studying of dynamics of temperature of a forehead skin. Regularly training 20 men have taken part in the research--sportsmen of various specializations (skiers, rock-climbers, boxers, etc.). Temperature of forehead skin was registered by infrared thermovision chamber Nec TH 9100SL. These results compared with the data of measurements of heart rate, gas exchange, the lactate concentration in peripheral blood, and also with anthropometrical characteristics. It was shown that on dynamics of skin temperature at maximal work load it was possible to divide all subjects into 2 unequal groups: 1 (2/3 subjects, the majority of which trains endurance) - after temperature decrease take place its smooth increase up to refusal ofwork; 2 (1/3 subjects, concerning various sports specializations)--from the moment of the beginning of active evaporation of sweat the temperature decreases to the work termination. In group 1 lactate threshold (lactate concentration in blood--4 mm/l) corresponds to the beginning of rise in temperature after its decrease as a result of sweat evaporation. In group 2 lactate threshold was necessary on a phase of decrease in temperature at the moment of active evaporation of sweat. Distinctions between groups in structure of correlation relationship between the measured indicators are revealed, inversion of a sign ofcorrelation quotient in some cases were shown. Thus significant distinctions between groups in the level of the working capacity indicators were not revealed. All it testifies to existence possibility at least two various successful strategy of urgent adaptation of system of thermoregulation to intense muscular work.     

Night work,light exposure and melatonin on work days and days off

We aimed to examine the effects of night work on salivary melatonin concentration during and subsequent to night work and the mediating role of light. We included 254 day workers and 87 night workers who were followed during 322 work days and 301 days off work. Each day was defined as the 24 hour period starting from the beginning of a night shift or from waking in the mornings with day work and days off. Light levels were recorded and synchronized with diary information (start and end of sleep and work). On average, participants provided four saliva samples per day, and these were analyzed for melatonin concentration by liquid chromatography tandem mass spectrometry (LC-MS/MS). Differences between day and night workers on work days and days off were assessed with multilevel regression models with melatonin concentration as the primary outcome. All models were stratified or adjusted by time of day. For light exposure, we estimated the total, direct and indirect effects of night work on melatonin concentrations obtaining 95% confidence intervals through bootstrapping. On work days, night workers showed 15% lower salivary melatonin concentrations compared with day workers (?15.0%; 95% CI: ?31.4%; 5.2%). During the night, light exposure mediated a melatonin suppression of approximately 6% (?5.9%, 95% CI: ?10.2%; ?1.5%). No mediating effect of light was seen during the day time. On days off, we observed no difference in melatonin concentrations between day and night workers. These findings are in accordance with a transient and partly light-mediated effect of night work on melatonin production.     

The origin of life: what we know,what we can know and what we will never know

The origin of life (OOL) problem remains one of the more challenging scientific questions of all time. In this essay, we propose that following recent experimental and theoretical advances in systems chemistry, the underlying principle governing the emergence of life on the Earth can in its broadest sense be specified, and may be stated as follows: all stable (persistent) replicating systems will tend to evolve over time towards systems of greater stability. The stability kind referred to, however, is dynamic kinetic stability, and quite distinct from the traditional thermodynamic stability which conventionally dominates physical and chemical thinking. Significantly, that stability kind is generally found to be enhanced by increasing complexification, since added features in the replicating system that improve replication efficiency will be reproduced, thereby offering an explanation for the emergence of life''s extraordinary complexity. On the basis of that simple principle, a fundamental reassessment of the underlying chemistry–biology relationship is possible, one with broad ramifications. In the context of the OOL question, this novel perspective can assist in clarifying central ahistoric aspects of abiogenesis, as opposed to the many historic aspects that have probably been forever lost in the mists of time.     

The capacity of fetal calf serum to support a primary antibody response in vitro is determined,in part,by its reduced glutathione content

Fetal calf serum (FCS) is unique among mammalian sera in its ability to support a primary antibody response, in vitro, by murine spleen cells. Another property unique to FCS among mammalian sera is its content of the tripeptide, glutathione. Since glutathione has a number of physiological functions important to cell function and survival, we have studied the possible relationship between the glutathione content of FCS and the ability of FCS to support a primary antibody response, in vitro. Our findings indicate that the capacity of FCS to support the murine spleen cell primary antibody response, in vitro, is, in part a function of its reduced glutathione (GSH) content, since: (a) GSH concentration correlates directly and definitively with the capacity of a lot of FCS to support an antibody response; (b) oxidation of GSH by heating a supportive FCS diminishes the supportive capacity of that FCS; and (c) such a treated FCS can be reconstituted to full supportiveness by appropriate doses of GSH. We postulate that reduced glutathione achieves this effect by scavenging lipid hydroperoxides generated by the action of oxygen-derived free radicals in the cell cultures.     

Skin temperature and lactate threshold during muscle work in athletes

The goal of the study was to evaluate the changes in the thermal state of the body during a maximal aerobic test on a bicycle ergometer on the basis of the dynamics of the skin temperature on the forehead. Twenty male athletes regularly training in various sports (skiers, rock-climbers, boxers, etc.) participated in our study. The forehead’s skin temperature was recorded using a NEC TH9100 Infrared Thermal Imaging Camera. These results were put together with the data on the heart rate, gas exchange, and lactate concentration in peripheral blood, as well as with anthropometrical parameters. It was shown that on the basis of the dynamics of the skin temperature at the maximal workload, the subjects could be divided into two groups of different sizes. In the first group (two-thirds of all subjects, most of the athletes of this group practiced endurance sports), after a temperature decrease, a smooth temperature increase took place until exhaustion. In the second group (one-third of all subjects, athletes of various sports specializations), from the beginning of active sweat evaporation, the temperature decreased until exhaustion. In the first group, the lactate threshold (a blood lactate concentration of 4 mmol/l) corresponded to the beginning of the increase in temperature after its decrease as a result of sweat evaporation. In the second group, the lactate threshold corresponded to the phase of the decrease in temperature during active sweat evaporation. The differences between the groups were expressed in the correlations of the measured parameters; in a number of cases, the inversions of the signs of correlation were found. At the same time, no significant differences in the parameters of working capacity were found between two groups. All these findings indicate the possibility of at least two successful strategies of urgent adaptation of the thermoregulatory system to intense muscular work.     

Biodiversity indicators: graphical techniques, smoothing and searching for what makes relationships work

Knowledge of the distribution of biodiversity remains poor. This situation might more readily be resolved If the species richness of certain groups of organisms indicated the richness of other, less well known groups. A spatially explicit exploration of the pattern in the predictive power that one taxon (a potential'indicator group") might have for the diversity of another has been performed previously. In this paper we respond to three important points that have been raised. First, we describe an additional graphical technique for visualising spatial aspects of indicator relationships. Second, we examine some of the consequences of smoothing species richness data on observed indicator relationships. Third, we consider some of the factors that may contribute to strong indicator relationships.     

Effects of the dietary supplements, activated charcoal and copper chlorophyllin, on urinary excretion of trimethylamine in Japanese trimethylaminuria patients

Trimethylaminuria (TMAU) is a metabolic disorder characterized by the inability to oxidize and convert dietary-derived trimethylamine (TMA) to trimethylamine N-oxide (TMAO). This disorder has been relatively well-documented in European and North American populations, but no reports have appeared regarding patients in Japan. We identified seven Japanese individuals that showed a low metabolic capacity to convert TMA to its odorless metabolite, TMAO. The metabolic capacity, as defined by the concentration of TMAO excreted in the urine divided by TMA concentration plus TMAO concentration, in these seven individuals ranged from 70 to 90%. In contrast, there were no healthy controls examined with less than 95% of the metabolic capacity to convert TMA to TMAO. The intake of dietary charcoal (total 1.5 g charcoal per day for 10 days) reduced the urinary free TMA concentration and increased the concentration of TMAO to normal values during charcoal administration. Copper chlorophyllin (total 180 mg per day for 3 weeks) was also effective at reducing free urinary TMA concentration and increasing TMAO to those of concentrations present in normal individuals. In the TMAU subjects examined, the effects of copper chlorophyllin appeared to last longer (i.e., several weeks) than those observed for activated charcoal. The results suggest that the daily intake of charcoal and/or copper chlorophyllin may be of significant use in improving the quality of life of individuals suffering from TMAU.     

The relation of the reactivity of the human respiratory system, mental and physical work capacity and metabolic characteristics during a 1-year stay in the mountains

People with the highest rates of mental working capacity staying for a year at an altitude of 1680 m below sea level are characterized by less pronounced responses of respiration to moderate hypoxia and great ventilatory response to maximally endured hypoxic action, by higher glucose content in blood and physical working capacity. Many relationships typical of the middle mountains are inverse ones under conditions of a one-year stay at an altitude of 3650 m below sea level. In the case of a total decrease in indices of mental and physical working capacity people with the highest rate of information processing are characterized by less reactivity of the respiratory system, greater resistance to ultimate hypoxia, lower glucose concentration, less physical working capacity.     

Management of dietary essential metals (iron,copper, zinc,chromium and manganese) by Wistar and Zucker obese rats fed a self-selected high-energy diet

The balances and content of essential elements (iron, copper, zinc, chromium and manganese) in the body of Wistar, Zucker lean and Zucker obese rats fed a reference or cafeteria diet from day 30 to 60 after birth have been studied. Intestinal iron absorption compensated for low iron content of the cafeteria diet and the extra needs of growth and fat deposition. It can be assumed that the altered energy regulation processes that afflict the genetically obese rat are not directly related to altered iron metabolism. Obese Zucker rats had lower copper tissue concentrations than lean rats, but when fed a cafeteria diet the differences between Zucker rats strains disappear. This cannot be traced to large differences in diet copper concentration. A low diet availability of zinc—such as that of cafeteria-fed fa/fa rats—is easily compensated for by increasing absorption. So, as a consequence, we can conclude that genetic obesity did not impair zinc absorption. There was no deficit of zinc in any of the groups studied; the rats have enough capacity to extract zinc within a wide range of dietary concentrations. The absorption of dietary chromium was inversely proportional to its concentration. The ability to extract chromium from the diet and the very low urinary losses are a consequence of its scarcity in most dietary items. Despite wide variations in the manganese of the diets, the absorption rates were practically unchanged except for obese rats fed the cafeteria diet. It seems that this low absorptive capacity is enough to supply the rat with the manganese it needs, since a sizeable—but subjected to 8-fold-span variations-proportion is lost in the urine. This alone points towards a considerable excess of manganese in both diets studied. Obesity does not have a significant effect on the abilities to absorb and retain minerals, since these processes were more related to dietary availability. Management of essential metals by obese rats depends whether this condition is genetic or induced by diet. Most of the differences observed can be related to differences in diet concentration, to the excess fat content or different metabolic attitude to use substrates of obese animals. The data presented show that the cafeteria diet used adequately serves the mineral needs of the rat, since the rat adapts its absorbing and retaining strategies to match the dietary availability of these minerals.     

Glioblastoma: Therapeutic challenges, what lies ahead

Glioblastoma (GBM) is one of the most aggressive human cancers. Despite current advances in multimodality therapies, such as surgery, radiotherapy and chemotherapy, the outcome for patients with high grade glioma remains fatal. The knowledge of how glioma cells develop and depend on the tumor environment might open opportunities for new therapies. There is now a growing awareness that the main limitations in understanding and successfully treating GBM might be bypassed by the identification of a distinct cell type that has defining properties of somatic stem cells, as well as cancer-initiating capacity - brain tumor stem cells, which could represent a therapeutic target. In addition, experimental studies have demonstrated that the combination of antiangiogenic therapy, based on the disruption of tumor blood vessels, with conventional chemotherapy generates encouraging results. Emerging reports have also shown that microglial cells can be used as therapeutic vectors to transport genes and/or substances to the tumor site, which opens up new perspectives for the development of GBM therapies targeting microglial cells. Finally, recent studies have shown that natural toxins can be conjugated to drugs that bind to overexpressed receptors in cancer cells, generating targeted-toxins to selectively kill cancer cells. These targeted-toxins are highly effective against radiation- and chemotherapy-resistant cancer cells, making them good candidates for clinical trials in GBM patients. In this review, we discuss recent studies that reveal new possibilities of GBM treatment taking into account cancer stem cells, angiogenesis, microglial cells and drug delivery in the development of new targeted-therapies.     

Pseudouridine in RNA: what, where, how, and why

Pseudouridine (5-ribosyluracil) is a ubiquitous yet enigmatic constituent of structural RNAs (transfer, ribosomal, small nuclear, and small nucleolar). Although pseudouridine (psi) was the first modified nucleoside to be discovered in RNA, and is the most abundant, its biosynthesis and biological roles have remained poorly understood since its identification as a "fifth nucleoside" in RNA. Recently, a combination of biochemical, biophysical, and genetic approaches has helped to illuminate the structural consequences of psi in polyribonucleotides, the biochemical mechanism of U-->psi isomerization in RNA, and the role of modification enzymes (psi synthases) and box H/ACA snoRNAs, a class of eukaryotic small nucleolar RNAs, in the site-specific biosynthesis of psi. Through its unique ability to coordinate a structural water molecule via its free N1-H, psi exerts a subtle but significant "rigidifying" influence on the nearby sugar-phosphate backbone and also enhances base stacking. These effects may underlie the biological role of most (but perhaps not all) of the psi residues in RNA. Certain genetic mutants lacking specific psi residues in tRNA or rRNA exhibit difficulties in translation, display slow growth rates, and fail to compete effectively with wild-type strains in mixed culture. In particular, normal growth is severely compromised in an Escherichia coli mutant deficient in a pseudouridine synthase responsible for the formation of three closely spaced psi residues in the mRNA decoding region of the 23S rRNA. Such studies demonstrate that pseudouridylation of RNA confers an important selective advantage in a natural biological context.     

Adsorption,Bioavailability, and Toxicity of Cadmium to Soil Microorganisms

The influence of adsorption on cadmium toxicity to soil microorganisms in soils was quantified as a function of solution and sorbent characteristics. The influence of adsorption on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. The sequence of relative percentage of FDA hydrolysis was reference smectite (RS) > untreated Vertisol (UV) > dithionate-citrate-bicarbonate (DCB)-treated Vertisol (DV) > H₂O₂-treated Vertisol (HV) in suspensions containing the same total Cd concentrations. The correlation between the percentage of FDA hydrolysis and activity of Cd²⁺ _(aq) illustrates that RS has a higher capacity of Cd adsorption. The microbial activity of RS was higher and the toxicity was lower than that of other soil samples. The HV had lower capacity of Cd adsorption so that its FDA hydrolysis was low and the Cd toxicity was high.     

造林再造林、森林采伐、气候变化、CO2浓度升高、火灾和虫害对森林固碳能力的影响

森林生态系统具有吸收大气CO_2、缓解气候变化的作用。造林再造林作为京都议定书认可的大气CO_2减排途径,是提高森林固碳能力的低成本、有效策略。森林生态系统固碳能力还受森林采伐、气候变化、大气CO_2浓度升高、火灾以及虫害等自然因素和人为因素的强烈影响。综述了全球和区域造林再造林的固碳能力,以及目前较受重视的一些因素(森林采伐、气候变化、大气CO_2浓度升高、火灾以及虫害)对森林生态系统固碳能力的影响。结果表明,全球造林再造林固碳能力为148—2400TgC/a;采伐造成的全球森林碳损失最大为900 TgC/a,其次是火灾为300 TgC/a,虫害造成森林碳释放最小在2—107 TgC/a之间。建议在今后的研究中,应关注固碳措施和多种环境因素对森林生态系统固碳能力,尤其是对森林土壤固碳能力的影响,严格控制森林采伐和火灾发生,以及减少或避免造林再造林活动引起的碳泄漏。     

Gendering unemployment in postsocialist Germany: ‘what I do is work,even if it's not paid’

This article uses feminist theories of the family to examine women's unemployment in the early years of German postsocialism. It is based on qualitative fieldwork, including 80 in-depth interviews, conducted in three cities in the formerly socialist region of Germany. In this article, three cases of couples coping with a wife's unemployment are analyzed in terms of micro-processes of negotiating work-family balance, redefining employment and domesticity, and reconstructing gendered identities. The central argument is that a couple's stance on emerging market institutions shaped how they re-negotiated their gender division of labor during postsocialism.     

Lag-time measurement of antioxidant capacity using myoglobin and 2, 2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid): rationale, application, and limitation.

The application of a simple lag-time assay for antioxidant capacity using myoglobin and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) or ABTS has been studied for its general application conditions. In the presence of an antioxidant, the ABTS(*+) radical-cation-forming chromogenic reaction, catalyzed by myoglobin and initiated by hydrogen peroxide (H(2)O(2)), has a lag period, and its duration is linearly correlated to the concentration of that antioxidant. The high linearity between the lag time and the antioxidant concentration remained unchanged regardless of the assay conditions. It was also found that the linearity was better for antioxidants at lower concentrations. The change of assay condition could significantly affect the relative antioxidant value of a chemical to the standard (ascorbic acid), although not to a large extent. Most of antioxidants investigated were found suitable to be assayed using this method. Some antioxidants, e.g., genistein, however, were not, probably due to their low reactivity toward ferrylmyoglobin or ABTS(*+). In conclusion, the lag-time assay is a reliable method for measuring the antioxidant capacity, provided caution is taken for antioxidants that mainly act through lowering the rate of the chromogenic reaction.     

Ribozymes: Flexible molecular devices at work

The discovery of ribozymes, RNAs with catalytic activity, revealed the extraordinary characteristic of this molecule, and corroborated the idea that RNA was the first informative polymer. The “RNA world” hypothesis asserts that the DNA/RNA/PROTEIN world arose from an earlier RNA world in which were present only RNA molecules able to perform both of the two functions performed separately by DNA and proteins in the present-day cells: the ability to transfer genetic information and to carry out catalytic activity.The catalytic properties of ribozymes are exclusively due to the capacity of RNA molecules to assume particular structures. Moreover, the structural versatility of RNA can allow to a single RNA sequence to fold in more than one structure, able to perform more than one function. In the first part of this work we will discuss the RNA plasticity, focusing on “bifunctional” ribozymes isolated by in vitro selection experiments, and on the consequences of this plasticity in the prospective of the emergence of new specific functions.The possibility that one sequence could have more than one structure/function, greatly increase the evolutionary potential of RNA, and the capacity of RNA to switch from a structure/function to another is probably one of the reasons of the evolutionary success also in modern-day cells. Naturally occurring ribozymes discovered in contemporary cells, demonstrate the crucial role that ribozymes still have in the modern protein world. In the second part of this paper we will discuss the capacity of natural ribozymes to modulate gene expression making use of their exclusive catalytic properties. Moreover, we will consider the possibility of their ancient origin.