Probit and survival analysis of tooth emergence ages in a mixed-longitudinal sample of chimpanzees (Pan troglodytes).

Tooth emergence data from a mixed-longitudinal sample of 58 chimpanzees of known age were analyzed using probit and survival techniques to produce median emergence ages, ranges of variability, and emergence sequences for primary and permanent teeth. Between-group comparisons were made to test for statistically significant differences in emergence ages. No such differences were found between right and left sides, or between maxilla and mandible, for any primary or permanent teeth. Male-female comparisons did demonstrate significant emergence-age differences for some teeth, although they were not always bilaterally symmetrical. More complete data are required to further clarify the nature of sex differences in tooth emergence in chimpanzees. Regression models for age prediction from the number of emerged teeth were generated and indicate that males achieve a given number of emerged teeth at a significantly later age than females. However, when fewer than five teeth have emerged, males are predicted to be younger than females. The sizable root mean square error values for these models suggest that this method of age prediction has limited usefulness owing to the amount of variability in timing of tooth emergence in chimpanzees. The implications of these data for studies on tooth emergence in early hominids are addressed.     

Gametocyte sex ratio of a malaria parasite: experimental test of heritability

The gametocyte sex ratio of Plasmodium mexicanum, a malaria parasite of western fence lizards, was studied in a modified garden experiment. Each of 6 naturally infected lizards was used to initiate 20 replicate-infections in naive western fence lizards. A significant donor effect was observed for the sex ratios of recipient infections at their maximal parasitemia, and this effect was associated with the sex ratio of the donor infection. In 20 infections in which sex ratio was followed during the course of the infection, 9 revealed constant sex ratios and 11 showed an increase in proportion of males over time. Recipient sex ratio was correlated with another life-history trait, a composite of rate of asexual replication and peak parasitemia, such that higher Rate-Peak scores were associated with infections with less female-biased sex ratios. These results are placed into the context of sex ratio theory that concludes that the degree of selfing of parasite genotypes (number of parasite clones) within the vector will influence the evolution of gametocyte sex ratio. The theory predicts that the sex ratio should be under some genetic control and thus be heritable as observed in the experiment. Clonal diversity should also influence the life-history trait, Rate-Peak, which was found to be correlated with sex ratio.     

Influence of sex of antecedent siblings on the human sex ratio

Analysis of family configurations in a population of 649,366 American secondary school students confirmed that sex of later-born children is influenced by the sex of antecedent siblings. Antecedent brothers decrease the probability of subsequent male births. This observation, a confirmation of an earlier report in a substantially smaller sample, is consistent with an immunologic influence on human sex determination.     

The effects of sex hormones on immune function: a meta‐analysis

The effects of sex hormones on immune function have received much attention, especially following the proposal of the immunocompetence handicap hypothesis. Many studies, both experimental and correlational, have been conducted to test the relationship between immune function and the sex hormones testosterone in males and oestrogen in females. However, the results are mixed. We conducted four cross‐species meta‐analyses to investigate the relationship between sex hormones and immune function: (i) the effect of testosterone manipulation on immune function in males, (ii) the correlation between circulating testosterone level and immune function in males, (iii) the effect of oestrogen manipulation on immune function in females, and (iv) the correlation between circulating oestrogen level and immune function in females. The results from the experimental studies showed that testosterone had a medium‐sized immunosuppressive effect on immune function. The effect of oestrogen, on the other hand, depended on the immune measure used. Oestrogen suppressed cell‐mediated immune function while reducing parasite loads. The overall correlation (meta‐analytic relationship) between circulating sex hormone level and immune function was not statistically significant for either testosterone or oestrogen despite the power of meta‐analysis. These results suggest that correlational studies have limited value for testing the effects of sex hormones on immune function. We found little evidence of publication bias in the four data sets using indirect tests. There was a weak and positive relationship between year of publication and effect size for experimental studies of testosterone that became non‐significant after we controlled for castration and immune measure, suggesting that the temporal trend was due to changes in these moderators over time. Graphical analyses suggest that the temporal trend was due to an increased use of cytokine measures across time. We found substantial heterogeneity in effect sizes, except in correlational studies of testosterone, even after we accounted for the relevant random and fixed factors. In conclusion, our results provide good evidence that testosterone suppresses immune function and that the effect of oestrogen varies depending on the immune measure used.     

Technical note: estimating sex using cervical canine odontometrics: a test using a known sex sample

The size of the permanent human canine tooth is one of the few sexually dimorphic features to be present in childhood and as such offers the opportunity to assist in the identification of sex in remains where no other appropriate criteria exist, such as in subadults. However, canine odontometrics are often associated with high levels of interobserver error and can be difficult to access if dentition is in situ. Additionally, appropriate points of measurement can be difficult to identify if the tooth is worn. Alternate measurements of the cervical canine diameters have been proposed as solutions to these issues, but the utility of these measurements in estimating sex has not been conclusively demonstrated. This study uses the buccolingual and mesiodistal cervical diameter of the canines from a known-sex sample from St. Bride's Church, London and a partially known-sex sample from the Old Church, Chelsea, London to classify individuals as male or female. A discriminant function classification using these diameters successfully identifies sex in 93.8% of the known-sex assemblage and 95% of the partially osteologically estimated sex assemblage. It is suggested that cervical canine diameters are highly repeatable measurements with low interobserver error, can be obtained on worn and in situ teeth, and provide as good or better guidance on estimating sex in human remains as standard maximal diameters.     

Age effects and secular trend in a cross-sectional sample: application to four head dimensions in Belgian adults

If longitudinal studies represent the more direct way to analyze modifications resulting from aging, often for obvious reasons cross-sectional samples can also be used for this purpose. But in this case differences between age groups cannot be identified with the effects of age only; they can also be attributed to the effects of a secular trend. It is the aim of this study to show, using four cephalic dimensions and a cross-sectional sample, the need to take into account the effect of a secular trend when the age effect is studied. In 1985 a study of head and facial measurements of 182 Belgian men, aged 25-54 years, was carried out. A simple comparison between different age groups (F tests) revealed significant differences for head breadth and facial breadths. However, no difference for head length was observed. The amplitude of the secular trend in the Belgian population is already known; thus an easy calculation is proposed to define the effects of the age factor. For head breadth the whole difference seems to be the result of the important decrease of secular trend, whereas the global increase observed for the bizygomatic and bigonial breadths results in part from the decrease resulting from the secular trend and in part from the increase resulting from the age effect.     

Maternal effects and heritability of annual productivity

Within-individual consistency and among-individual heterogeneity in fitness are prerequisites for selection to take place. Within-individual variation in productivity between years, however, can vary considerably, especially when organisms become older and more experienced. We examine individual consistency in annual productivity, the covariation between survival and annual productivity, and the sources of variation in annual productivity, while accounting for advancing age, to test the individual-quality and resource-allocation life-history theory hypotheses. We use long-term data from a pedigreed, wild population of house sparrows. Within-individual annual productivity first increased and later decreased with age, but there were no selective mortality due to individual quality and no correlation between lifespan and productivity. Individuals were consistent in their annual productivity (C = 0.49). Narrow-sense heritability was low (h(2) = 0.09), but maternal effects explained much of the variation (M = 0.33). Such effects can influence evolutionary processes and are of major importance for our understanding of how variation in fitness can be maintained.     

Species-level heritability reaffirmed: a comment on "on the heritability of geographic range sizes"

For many current issues in macroevolution and macroecology, it is important to know to what degree the attributes of species are shared among closely related lineages, a concept sometimes referred to as species-level heritability. Recently, Webb and Gaston proposed a new method for analyzing the heritability of geographic range size and concluded that range size is not heritable in Cretaceous gastropods (data from Jablonski) and modern birds (their data). Here we show that Webb and Gaston's method is flawed in that it implicitly assumes that range sizes are uniformly distributed. When range size distributions show their characteristic strong right skew, Webb and Gaston's method spuriously tends to find that range sizes of closely related pairs of species are more dissimilar than the random expectation. A reanalysis of Jablonski's data finds range size to be robustly and strongly heritable in Cretaceous gastropods and less strongly but still significantly heritable in present-day birds.     

The influence of sex, age and heritability on human skeletal muscle carnosine content

The dipeptide carnosine is found in high concentrations in human skeletal muscle and shows large inter-individual differences. Sex and age are determining factors, however, systematic studies investigating the sex effects on muscle carnosine content throughout the human lifespan are lacking. Despite the large inter-individual variation, the intra-individual variation is limited. The question may be asked whether the carnosine content is a muscle characteristic which may be largely genetically determined. A total of 263 healthy male and female subjects of 9-83 years were divided into five different age groups: prepubertal children (PC), adolescents (A), young adults (YA), middle adults (MA) and elderly (E). We included 25 monozygotic and 22 dizygotic twin pairs among the entire study population to study the heritability. The carnosine content was measured non-invasively in the gastrocnemius medialis and soleus by proton magnetic resonance spectroscopy (1H-MRS). In boys, carnosine content was significantly higher (gastrocnemius 22.9%; soleus 44.6%) in A compared to PC, while it did not differ in girls. A decrease (~16%) was observed both in males and females from YA to MA. However, elderly did not have lower carnosine levels in comparison with MA. Higher correlations were found in monozygotic (r=0.86) compared to dizygotic (r=0.51) twins, in soleus muscle, but not in gastrocnemius. In conclusion, this study found an effect of puberty on muscle carnosine content in males, but not in females. Muscle carnosine decreased mainly during early adulthood and hardly from adulthood to elderly. High intra-twin correlations were observed, but muscle-dependent differences preclude clear conclusions toward heritability.     

Horizontal transfer of bacterial symbionts: heritability and fitness effects in a novel aphid host

Members of several bacterial lineages are known only as symbionts of insects and move among hosts through maternal transmission. Such vertical transfer promotes strong fidelity within these associations, favoring the evolution of microbially mediated effects that improve host fitness. However, phylogenetic evidence indicates occasional horizontal transfer among different insect species, suggesting that some microbial symbionts retain a generalized ability to infect multiple hosts. Here we examine the abilities of three vertically transmitted bacteria from the Gammaproteobacteria to infect and spread within a novel host species, the pea aphid, Acyrthosiphon pisum. Using microinjection, we transferred symbionts from three species of natural aphid hosts into a common host background, comparing transmission efficiencies between novel symbionts and those naturally infecting A. pisum. We also examined the fitness effects of two novel symbionts to determine whether they should persist under natural selection acting at the host level. Our results reveal that these heritable bacteria vary in their capacities to utilize A. pisum as a host. One of three novel symbionts failed to undergo efficient maternal transmission in A. pisum, and one of the two efficiently transmitted bacteria depressed aphid growth rates. Although these findings reveal that negative fitness effects and low transmission efficiency can prevent the establishment of a new infection following horizontal transmission, they also indicate that some symbionts can overcome these obstacles, accounting for their widespread distributions across aphids and related insects.     

Indian Biotech Bazaar: a swot analysis

Biotechnology is a life science-based technique especially used in agriculture, medicine and food sciences. It is generally defined as the manipulation in organisms to generate products for the welfare of the world. Biotechnology combines disciplines such as genetics, biochemistry, microbiology, and cell biology along with information technology, chemical engineering, robotics etc. It includes basic industries such as food processing, tissue culture, plant development and other sophisticated ones such as recombinant therapeutics and diagnostics. Biotechnology, globally recognized as a rapidly emerging and far-reaching technology, is aptly described as the "technology of hope" for its promise of food, health and environmental sustainability. In India, biotechnology employs more than 10 000 people and generates roughly US$ 500 million in revenue annually. The biotechnology market has increased its sales from Rs. 50 billion in 1997 to Rs.70 billion in 2000, and is expected to cross Rs. 240 billion by the year 2010. In India, the human health biotech products account for 60% of the total market; agribiotech and veterinary 25%, medical devices, contract research and development (R&D), reagents and supplies constitute the remaining 15% Moreover, to facilitate foreign investment, capital and government policies are being revised. Other important industries include industrial enzyme manufacture, bioinformatics, and medical devices. Biotechnology has had limited appeal so far on our capital markets, and we have less then a dozen biotech companies listed on the public markets.     

GENESiS: creating a composite index of the vulnerability to anxiety and depression in a community-based sample of siblings.

There is considerable evidence for a unitary and dimensional view of the genetic vulnerability to symptoms of anxiety and depression. The GENESiS (Genetic Environmental-Nature of Emotional States in Siblings) Study aims to use a multivariate approach to detect genetic loci that contribute to individual differences in this vulnerability dimension. The study used the UK General Practice Research Framework to generate a community-based sample of siblings. Questionnaire measures of anxiety/depression included the short form of the neuroticism scale from the revised Eysenck Personality Questionnaire (EPQ-N), the General Health Questionnaire (GHQ-12), and the anxious arousal and high positive affect subscales from the Mood and Anxiety Symptoms Questionnaire (MASQ-AA and MASQ-HPA). Genetic model-fitting of 2658 unselected sibships provided evidence for a single common genetic (familial) factor that accounted for a substantial proportion of the genetic variances and covariances of these four measures. Using the parameter estimates of this model, we constructed a composite index of this common genetic factor. This index, which has a sib correlation of 0.22, will be used as a quantitative phenotype in the molecular genetic phase of GENESiS.     

Three-dimensional geometric morphometric analysis of cranio-facial sexual dimorphism in a Central European sample of known sex

This article presents an approach for estimating the sexual dimorphism of adult crania using three-dimensional geometric morphometric methods. The study sample consisted of 139 crania of known sex (73 males and 66 females) belonging to persons who lived during the first half of the 20th century in Bohemia. The three-dimensional co-ordinates of 82 ecto-cranial landmarks and 39 semi-landmarks covering the midsagittal curve of the cranial vault were digitised using a MicroScribe G2X contact digitiser. The purposes of the investigation were to define the regions of the cranium where sexual dimorphism is most pronounced and to investigate the effectiveness of this method for determining sex from the shape of the cranium. The results demonstrate that it is better to analyse apportionable parts of the cranium rather than the cranium as a whole. Significant sexual differences (significance was determined using multivariate analysis of variance) were noted in the shape of the midsagittal curve of the vault, upper face, the region of the nose, orbits, and palate. No differences were recorded either in the shape of the cranium as a whole or in the regions of the base and the neurocranium. The greatest accuracy in determining sex was found in the region of the upper face (100% of study subjects correctly classified) and the midsagittal curve of the vault (99% of study subjects correctly classified).     

Perceptions and preferences on denture marking in an Indian sample

doi: 10.1111/j.1741‐2358.2011.00499.x Perceptions and preferences on denture marking in an Indian sample Aim: Denture marking is useful in institutional settings and post‐mortem identification. Numerous markers have been developed, and their advantages and limitations assessed previously; however, patient perception to denture marking is paramount. We evaluated this in an Indian sample and also gauged their preference for different markers. Materials and methods: One‐hundred and one edentulous patients seeking prosthodontic treatment in our institution were shown four denture markers (stainless steel matrix band, paper strip with name inscribed on it, patient photograph and optically readable laminated bar code) and asked whether they wanted similar markers in their dentures; patients were also asked to rank the markers based on preference and indicate their satisfaction with it. Results: Approximately two‐thirds of patients (65/101) were uninterested in getting their dentures marked; among the 36 who agreed, 10 preferred the stainless steel band followed by photographs (9), paper strip (6) and bar code (2); nine gave multiple responses and were excluded from analyses. Sixteen patients expressed dissatisfaction with the photographic marker and bar code, while this number reduced for the stainless steel band (13) and paper strip (10). Conclusions: The results are in contrast to European studies wherein the majority of patients agreed to denture marking, indicating patient background (e.g. education level) may affect perception to denture marking; amongst those who agreed to marking, most preferred, or were satisfied with, the stainless steel and paper strip markers over photographic marker and a complex method such as bar‐coding, implying that simple methods harbouring basic patient information may suffice in the Indian context.     

Multifactorial etiology of cervical cancer: a hypothesis

Cancer of the cervix is the second most common life-threatening cancer among women worldwide, with incidence rates ranging from 4.8 per 100,000 women per year in the Middle East to 44.3 per 100,000 in East Africa. Epidemiologic and clinical data demonstrate that human papillomaviruses (HPV), especially HPV-16 and HPV-18, play at least a major if not a necessary role in the etiology of cervical cancer. However, many investigators acknowledge that HPV is not sufficient to induce cervical cancer and that a multifactorial etiology is likely. HPV can be found in a growing proportion of patients with cervical cancer, approaching 100%, but is not yet found in every patient with disease. Other factors, such as herpes simplex virus type 2 infections, cigarette smoking, vaginal douching, nutrition, and use of oral contraceptives, have been proposed as contributing factors. In the first half of the 20th century, Peyton Rous and colleagues demonstrated the joint action of tars and Shope papillomavirus to consistently induce squamous cell carcinomas in rabbits. Using the Rous model as a prototype, one might hypothesize that some cases of cervical cancer arise from an interaction between oncogenic viruses and cervical tar exposures. Cervical tar exposures include cigarette smoking, use of tar-based vaginal douches, and long years of inhaling smoke from wood- and coal-burning stoves in poorly ventilated kitchens.     

Intralocus sexual conflict,adaptive sex allocation,and the heritability of fitness

Intralocus sexual conflict arises when selection favours alternative fitness optima in males and females. Unresolved conflict can create negative between‐sex genetic correlations for fitness, such that high‐fitness parents produce high‐fitness progeny of their same sex, but low‐fitness progeny of the opposite sex. This cost of sexual conflict could be mitigated if high‐fitness parents bias sex allocation to produce more offspring of their same sex. Previous studies of the brown anole lizard (Anolis sagrei) show that viability selection on body size is sexually antagonistic, favouring large males and smaller females. However, sexual conflict over body size may be partially mitigated by adaptive sex allocation: large males sire more sons than daughters, whereas small males sire more daughters than sons. We explored the evolutionary implications of these phenomena by assessing the additive genetic (co)variance of fitness within and between sexes in a wild population. We measured two components of fitness: viability of adults over the breeding season, and the number of their progeny that survived to sexual maturity, which includes components of parental reproductive success and offspring viability (RS^V). Viability of parents was not correlated with adult viability of their sons or daughters. RS^V was positively correlated between sires and their offspring, but not between dams and their offspring. Neither component of fitness was significantly heritable, and neither exhibited negative between‐sex genetic correlations that would indicate unresolved sexual conflict. Rather, our results are more consistent with predictions regarding adaptive sex allocation in that, as the number of sons produced by a sire increased, the adult viability of his male progeny increased.