Sex-related Variation Research Articles

Feeding and Chewing Behaviours of Nubian Ibex: Compensation for Sex-Related Differences in Body Size

Size-related differences in digestive capabilities are thought to account for patterns of diet selection, social structure and habitat use by small- and large-bodied herbivores. We examined food processing behaviours that could compensate for digestive constraints resulting from the relative scaling of metabolic requirements and gut capacity with body mass. We observed feeding, chewing and ruminating behaviours of sexually size-dimorphic Nubian ibex fed diets chopped to a short (1-2 cm), medium (8 cm), or long (25 cm) length. These diets differed in the amount of oral processing needed for particle size reduction, bolus formation and swallowing. Food particle size did not affect intake rate (g/min) but chewing investment (chews/g) of both sexes was 30% less for the shortest hay. Rumination activity of both sexes approximated the maximum sustainable level of almost 10h/day for all diets. Chewing rates (chews/min) during rumination did not differ between males and females. Chewing investment of females was 40% greater than that of males while feeding and more than 50% greater while ruminating. Size-related differences in molar occlusal surface area (∼ 15%) were much too small to account for sex-related variation in chewing investment. Our results support the hypothesis that females enhanced digestion rates relative to those of larger-bodied males through increased oral processing.

Metabolism of Pyriproxyfen in Rats. 1. Absorption, Disposition, Excretion, and Biotransformation Studies with [phenoxyphenyl-14C]Pyriproxyfen

Male and female rats were given a single oral dose of [phenoxyphenyl- 14 C]pyriproxyfen [4-phenoxyphenyl (R,S)-2-(2-pyridyloxy)propyl ether] at 2 (low dose) or 1000 (high dose) mg/kg. 14 C was rapidly excreted into feces and urine, with the former route predominating (about 90% of the dose). Peak 14 C concentrations in blood, kidney, liver, and other tissues except for fat occurred 2-8 h after administration, being 0.4, 0.4, 2.5, and <0.2 μg of pyriproxyfen equivalents/g of tissue (ppm), respectively. Peak 14 C concentration in fat occurred 12-24 h after administration, being 0.3-0.5 ppm. 14 C tissue residues on the seventh day were below 0.02 and 10 ppm for the low and high doses, respectively. The major metabolic reactions were hydroxylation at the 2- or 4-position of the terminal phenyl ring, hydroxylation at the 5-position of the pyridyl ring, cleavage of the ether linkages, and conjugation of the resultant phenols with sulfuric acid. No marked sex-related differences were observed for 14 C excretion or 14 C tissue residues. However, a slight sex-related variation was found for the extent of metabolic reactions

Reproductive transfer and variation of body load of organochlorine pollutants with age in fin whales (Balaenoptera physalus)

The body load of tDDT (p,p'DDT + o,p'DDT + p,p'DDE + p,p'TDE) and polychlorinated biphenyls (sum of congeners) was estimated for 169 fin whales to study age and sex-related variation and to calculate the quantity of these compounds transferred to offspring through reproduction. Blubber was the body compartment containing the greatest quantities of organochlorines, but its relative contribution to total load was lower than in other cetaceans because in fin whales muscle and bone are also significant lipid reserve sites. In male fin whales, organochlorine body loads increased with age but tended to reach a plateau in fully grown individuals. In adult females, loads decreased with age because of transfer to offspring cancelling the rise in loads associated with body growth; as a consequence, the amount of organochlorines transferred during a reproductive cycle also declined with age. This transfer is lower than that found for other cetaceans because fin whales have a shorter lactation period. According to the calculations, the first offspring of a female fin whale receives about 1 g of PCB and about 1.5 g of tDDT. These amounts will progressively decrease in subsequent reproductive cycles to reach a minimum of 0.2 g PCB and 0.3 g tDDT in an old female. Therefore, the first calf delivered is the one most likely to be affected by pollutants.

Bioaccumulation of manganese in selected tissues of the freshwater crab, Potamonautes warreni (Calman), from industrial and mine-polluted freshwater ecosystems

Manganese concentrations in water and sediments of the Bronkhorstspruit River, Nooitgedacht Dam and especially in the Natalspruit River, did not fall within stated limits for the protection of aquatic life. Tissue manganese concentrations in Potamonautes warreni from the Natalspruit River were generally higher than those in the tissues of crabs from the other two aquatic ecosystems. The highest mean manganese tissue concentration in crabs from the three systems was detected in the carapace (587± 445 µg g-1 wet weight). It appears that the carapace in these animals acts as a sink in which manganese can be deposited, thus also playing an important role in the detoxification of manganese in these crustaceans. No seasonal or sex-related variation was detected. Body size of the crabs, however, seems to be an important influencing factor in manganese bioaccumulation. A significant increase in carapace manganese concentrations was detected with an increase in body size. However, muscle manganese concentrations were higher in the smaller groups. The concentration factors (BF) calculated for the different tissues with respect to the water were highest in the carapace and ranged from 280.9 to 742.8. The BF with respect to the sediment was comparatively low for all the tissues (0.1 to 0.7). As the manganese concentration in the tissues reflects to some extent the degree of manganese contamination of the surrounding aquatic environment, it appears that P. warreni may be useful as a potential biomonitor of manganese pollution.

BIOCHEMICAL HETEROZYGOSITY AND MORPHOLOGIC VARIATION IN A COLONY OF PAPIO HAMADRYAS HAMADRYAS BABOONS.

This analysis examines the association between genetic heterozygosity and individual morphologic variation in a captive population of Papio hamadryas hamadryas consisting of 403 juveniles and adults. The population structure of the colony was artificially generated and maintained and is thus rigorously defined. Subpopulations delimited by age, sex, and degree of inbreeding are also explored. Heterozygosity, as enumerated from six simple Mendelian biochemical loci, is compared with the residual morphologic variation of each individual for each of 20 quantitative traits. Use of a sequential Bonferroni technique nullifies all significant correlations. Principal-components analysis reduces the morphometrics to a single or few significant axes in each population. The first axis of the total population contains 86.07% of the variation in the sample and the absolute values of the factor scores exhibit a significant positive correlation with heterozygosity at P < 0.05. Correcting for age- and sex-related variation in the total population with a linear model subsequently demonstrates that no significant correlation between heterozygosity and morphologic variation exists. No significant relationship is found in the inbred animals or subpopulations when age and sex are controlled. Previous studies have indicated that individuals proximal to the population mean for a specific polygenic trait exhibit a higher biochemical heterozygosity than individuals distant from the mean. The results presented here, which are based on more loci than many studies and a well-defined population, do not support this relationship. Substructuring of a population by age and sex can lead to spurious correlations with univariate or multivariate techniques. Comprehensive indices of genetic variation and rigorous statistical techniques should be used in future analyses. Studies that fail to recognize these design elements should be interpreted with caution.

Relations between song repertoire size and the volume of brain nuclei related to song: comparative evolutionary analyses amongst oscine birds

Song and brain structure are compared amongst 41 species of oscine birds by using the method of independent evolutionary contrasts. We find a significant correlation between the relative volume of the song control centre, the high vocal centre (HVC), and the number of song types typically found in the repertoire. Relative HVC volume is not correlated with the number of different syllable types per song bout. The relative volume of a second song nucleus, area X, is not significantly correlated with either measure. Relative HVC volume is uncorrelated with relative volume of the hippocampus, a brain area involved in other forms of memory. This is the first evidence for repeated independent evolution of an association between complexity of learned song and the relative volume of one of the song control nuclei though to be involved in song learning.

Age- and sex-related variation of plasma endothelin-1 concentration in normal and hypertensive subjects

Age- and sex-related variation of plasma endothelin-1 concentration in normal and hypertensive subjects

Effects of Age, Sex, and Fat Level on Wing Loading in Dark-Eyed Juncos

-Ageand sex-related variation in aerodynamically important traits such as wing loading may contribute to behavioral variation within a population. Increased wing loading also may be an important cost of carrying extra body fat, placing constraints on viable strategies of migratory and winter fattening. Therefore, we quantified the effects of age, sex, and fat level on wing loading in Dark-eyed Juncos (Junco hyemalis). Female juncos had significantly greater wing loading than males; wing loading did not differ among age classes. Increased fat levels (as indicated by fat scores) increased wing loading in all age/sex classes, but females and adults showed significantly greater fat-related increases in wing loading than males and immatures. Increasing from lean body mass to a full fat load added approximately 14 to 16% to an individual's wing loading. Wing loading increased allometrically with lean body mass in juncos (heavier individuals have relatively greater wing loading). We found sexand fatrelated variation in wing loading that is probably sufficient to affect flight performance and, therefore, susceptibility to predation, strategies of fattening, and distribution among individual Dark-eyed Juncos. Received 7 December 1990, accepted 10 January 1992. WING loading, a fundamental component of avian wing design, affects speed, maneuverability, and energy expenditure during flight (Rayner 1988, Pennycuick 1989, Norberg 1990 and references therein). Because wing loading is an important determinant of flight performance, interspecific differences (particularly large-scale taxonomic differences) in wing loading can be associated with ecological and behavioral variation among taxa (Greenewalt 1962, 1975, Norberg 1979, 1986, 1990:241, Norberg and Norberg 1988, Rayner 1988). Within species, wing loading can exhibit ageand sex-specific variation (e.g. Blem 1975, Mueller et al. 1981). Furthermore, widespread intraspecific variation in wing length (e.g. Alatalo et al. 1984) and wing shape (Gaston 1974, Tiainen and Hanksi 1985, Hedenstrom and Pettersson 1986, Mulvihill and Chandler 1990) suggests that variation in wing loading within species is common. This raises the possibility of ecologically significant covariation of aerodynamically important traits such as wing loading with foraging behavior, susceptibility to predation, or migratory dynamics within a population. We analyzed intraspecific variation in wing loading in a passerine bird, the Dark-eyed Junco 3Present address: Department of Biological Sciences, University of Southern Mississippi, Southern Station, Box 5018, Hattiesburg, Mississippi 39406, USA. (Junco hyemalis). Predicting the extent or direction of possible differences in wing loading among age/sex classes of juncos is difficult, because wing loading is the result of an interaction among body mass, wing length, and wing shape (all of which are characters that show ageand sex-related variation in juncos; Nolan and Ketterson 1983, Mulvihill and Chandler 1990). Furthermore, the body mass of juncos is subject to considerable temporal variation (e.g. during migratory or winter fattening) that will influence wing loading (Nolan and Ketterson 1983, Chandler and Mulvihill, unpubl. data). In fact, increased wing loading may be an important cost of carrying extra body fat (Blem 1975, Stuebe and Ketterson 1982, Nolan and Ketterson 1983), placing constraints on viable strategies of migratory or winter fattening (Lima 1986, Alerstam and Lindstr6m 1990). Because of the potential ecological significance of ageand sexspecific variation in wing loading, and the hypothesized role of increased wing loading in constraining migratory and winter fattening, our objectives were: (1) to quantify ageand sexrelated differences in wing area and wing loading among Dark-eyed Juncos; (2) to determine the aerodynamic cost (in terms of increased wing loading) of increasing fat levels in a passerine bird; and (3) to characterize the intraspecific relationship between wing loading and body mass.

Vertebral body diameters and sex prediction.

As a direct consequence of the generally larger body size of the male, it is reasonable to expect the adult human vertebral column to display sexual dimorphism. However, there is a distinct paucity of literature concerning sex-related variation in vertebral dimensions. This study examines the accuracy with which sex may be predicted from vertebral body diameters. In a sample selected from a documental skeletal series, sex could be correctly assigned with an accuracy approaching 90%. This degree of sexual differentiation is of value for both the forensic and archeological identification of human skeletal remains. An interesting relationship was noted between the degree of expression of sexual dimorphism and the role of each area of the vertebral body in body weight transfer. The posterior aspect of the vertebral body is involved in the transmission of body weight both vertically and laterally from the transverse processes. This area was consistently less dimorphic than the anterior region of the vertebral body, which is more concerned with the transfer of body weight from the vertebra above.

Sex differences in the perception of noxious heat stimuli

This study compared pain perception in young male and female subjects, using experimental noxious heat stimuli. During 2 sessions, each of 40 subjects rated the magnitude of 120 heat stimuli, ranging from 45°C to 50°C. The study included a comparison of visual analogue and magnitude matching rating procedures, as well as a test of simulated analgesia, in which the range of stimuli presented during the 2 experimental sessions was shifted by 1°C. We found that females rated noxious heat stimuli as more intense than did males, independent of the gender of the experimenter or the type of rating scale. In addition, the data suggest that females discriminate among the painful heat intensities better than males. For example, female subjects showed significant between-session discrimination of noxious heat stimuli, while male subjects did not, and females produced steeper within-session stimulus-response functions than did males. These observed differences in nociceptive discrimination between males and females indicate that the sex-related variation in pain perception is probably related to sensory factors rather than differences in attitude or emotional response.

Sex-Related Variation in Growth Rate as a Result of Selection for Large Size and Protandry in a Bivoltine Butterfly, Pieris napi

This paper explores what factors influence size, development time and growth rate in a polyandrous and bivoltine butterfly, Pieris napi L. In butterflies male/female sexual size dimorphism has been shown to be positively correlated with female polygamy. Hence, males of P. napi should be selected for large size. Comparing time constraints between the directly developing and the diapause developing generations, it is obvious that the former is more pressed for time, having to complete two generation cycles in one season, whereas the latter only completes one life cycle. On top of this comes selection on males to emerge before females. Rearing larvae at the critical daylength, where part of the individuals develop directly and part diapause, a two-way ANOVA on growth rate shows that there is an interaction between sex and developmental pathway (...)

Magnetic resonance imaging (MRI) of normal bone marrow in children: Age and sex related variation in signal intensity

Magnetic resonance imaging (MRI) of normal bone marrow in children: Age and sex related variation in signal intensity

Seasonal and Sex-Related Variation in the Activity Patterns of Common Seals (Phoca vitulina)

Using the ten-day sunshine duration data of 107 meteorological stations in Henan Province from 1961 to 2012, spatial-temporal variation characteristics of ten-day sunshine duration were analyzed, and the scale invariance analysis of ten-day sunshine duration was studied by using the method of detrended fluctuation analysis. The results showed that the means of ten-day sunshine duration and its standardized error among stations were 57.90 and 9.18 h, respectively, and their probability distributions were not subject to normal distribution. The cumulative abnormal of sunshine duration had a distinct linear increasing trend, however, its square deviation among the stations was of phase characteristics. The scale index of ten-day sunshine of each station was above 0.5, indicated that time series of scale index was of permanence. Variation of scale index among stations was small, which obeyed the normal distribution.

Herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) infections in Saudi Arabia.

The seroepidemiology of infection due to herpes simplex type 1 (HSV-1) and varicella-zoster (VZV) viruses was investigated in 224 Saudi children aged from under 1 year to 15 years and 452 adults (healthy male blood donors and pregnant women) using a presently available sensitive indirect immunofluorescence technique to detect antibodies to these viruses in order to determine the age of primary infection. Age-specific prevalence of IgG antibodies to HSV-1 and VZV showed a progressive increase with age in both males and females with no obvious sex-related variation in the level. The overall prevalence of antibodies was 60 per cent for HSV-1 and 68 per cent for VZV in children whereas about 90 per cent of the adults showed the presence of antibodies to both viruses. Virological and serological confirmation of two cases in children of herpes simplex encephalitis (HSE) due to HSV-1 and VZV reactivation in two adults is described.

Intrahemispheric sex differences in the functional representation of language and praxic functions in normal individuals

Kimura (1980, The Behavioral and Brain Sciences, 3, 240–241; 1983, Canadian Journal of Psychology, 37, 19–35; 1987, Canadian Psychology, 28, 133–147) recently proposed that there are intrahemispheric sex differences in the organization of particular language and praxic functions such that in females these functions are more focally represented. This hypothesis, as well as supporting data, was derived from research with brain-injured subjects. The purpose of the present study was to test the utility of using dual-task methodology for investigating sex-related variation in intrahemispheric functional organization in normal individuals. Women were found to show greater interference than men on concurrent tasks of language and right-hand finger tapping. In support of Kimura's model, the present findings yielded evidence suggestive of intrahemispheric sex differences in the “functional distance” between language and praxic functions within the left hemisphere of normal individuals.

Irritant reactivity in males and females.

Repeated, daily, open sodium lauryl sulfate (SLS) applications caused slight alterations in transepidermal water loss (TEWL) and dielectric water content (DEWC) in males and females. No erythema developed. Inter-individual variation in skin reactivity was demonstrated; sex-related patterns in reactivity to open cumulative irritant exposure did not exist. In patch testing with 0.5 and 1% SLS, reflecting acute irritation capacity, the reaction pattern, assessed by TEWL, DEWC, laser Doppler velocimetry (LDV) and visual scoring (VS), differed from that induced by open, cumulative SLS irritation. Again, inter-individual variation in the reactivity was demonstrated; significant sex-related differences did not develop. Individual reactivity showed considerable variation in acute and cumulative irritant response and was greater than the sex-related variation. We did not identify responses demonstrating that women have delicate (easily irritated) skin, nor that males have "tougher" skin than females.

Biotransformation and induction: implications for toxicity, bioaccumulation and monitoring of environmental xenobiotics in fish.

Biotransformation of xenobiotics in fish occurs by many of the same reactions as in mammals. These reactions have been shown to affect the bioaccumulation, persistence, residue dynamics, and toxicity of select chemicals in fish. P-450-dependent monooxygenase activity of fish can be induced by polycyclic aromatic hydrocarbons, but phenobarbital-type agents induce poorly, if at all. Fish monooxygenase activity exhibits ideal temperature compensation and sex-related variation. Induction of monooxygenase activity by polycyclic aromatic hydrocarbons can result in qualitative as well as quantitative changes in the metabolic profile of a chemical. Induction can also alter toxicity. In addition, multiple P-450 isozymes have been described for several fish species. The biotransformation products of certain chemicals have been related to specific P-450 isozymes, and the formation of these products can be influenced by induction. Exposure of fish to low levels of certain environmental contaminants has resulted in induction of specific monooxygenase activities and monitoring of such activities has been suggested as a means of identifying areas of pollutant exposure in the wild.

Kinetic analysis of the center of gravity of the human body in normal and pathological gaits

The kinetics of the body's center of gravity during level walking were analyzed in 50 normal subjects and 47 patients. The three-dimensional displacements of the center of gravity were computed by the integration of force plate data. The energy levels and the power requirements of the center of gravity were also calculated, and the average and standard deviation of these variables were determined for normal and pathological gaits. The sex-related variation in normal gait, as suggested by previous force plate studies, was clearly demonstrated in our study. The parameters obtained from the displacements and the energy variations of the center of gravity are considered useful in the evaluation of stability and efficiency for pathological gaits.

Studies on serum cholinesterase isoenzymes in laboratory animals: Serum cholinesterase isoenzyme patterns and cholinesterase activities animal species.

We analyzed cholinesterase (ChE) isoenzyme patterns of various laboratory animal species using electrophoresis to explore possible species-related variations and also to determine if there is a relationship between the ChE activity and the ChE isoenzyme pattern.The laboratory animals that we used were Standard Wistar and Spraque-Dawley rats, Djungarian hamsters, Hartley guinea pigs, Japanese white rabbits (JW-NIBS strain), Beagle dogs, Japanese monkeys, Yorkshire pigs, Thoroughbred horses and Japanese quail. The ChE isoenzyme patterns were determined using polyacrylamide gradient gel electrophoresis (PAG-EP). The activity of serum ChE was measured using Ellman's method. The ChE isoenzymes of Wistar and Sprague-Dawley rats consisted of six separate fractions and sex- and/or age-related differences in the number of fractions were not observed. However, a sex-related variation was observed in the proportions of individual ChE isoenzyme bands for both rat strains. Also a sex-related difference was demonstrated in the serum ChE activity. The number of fractions of the ChE isoenzyme exhibited a species-related variations in the other animals. Hamsters, guinea pigs, rabbits, dogs, monkeys, pigs, horses and quails had 4, 3, 4, 3-5, 3, 3, 4 and 3 ChE isoenzyme bands, respectively. However, with the exception of the rats, the hamsters, guinea pigs, rabbits, dogs, monkeys, pigs, horses and quail did not show any sex-related difference in the proportions of their ChE isoenzyme bands or in the ChE activities.Therefore, it appears that there is a relationship between the serum ChE activity and the proportion of ChE isoenzyme bands. These results suggest a possible species-related variation in the mode of polymerization of serum ChE subunits that constitute the ChE isoenzymes.

Protein markers of nutrition status as related to sex and age.

We assessed age- and sex-related variation in those proteins commonly measured to evaluate protein catabolic losses in patients in acute care. We determined concentrations of iron and iron-binding capacity, transferrin, albumin, prealbumin, and retinol-binding protein in sera from 158 healthy blood donors and 48 hospitalized patients, then grouped the data according to age (by decade) and sex. There was no significant variation in either category. For the total nondiseased population the concentrations of three proteins (means SD, and range) were: transferrin, 2760, 510, 1740-3780 mg/L (population CV 18.5%); prealbumin, 296, 49, 200-390 mg/L (CV 16.6%); retinol-binding protein, 60, 127, 35-85 mg/L (CV 21.2%). Prealbumin and retinol-binding protein concentrations were highly correlated (r = 0.803). Because prealbumin can be easily monitored and its assay is subject to few interferences, we conclude that determination of prealbumin is suitable for assessing the existence and severity of nutritional metabolic deficits.