Genetic variance in dental dimensions of Punjabi twins

Genetic variance analysis of 56 tooth size traits was based on a sample of 58 pairs of twins (23 MZ and 35 DZ) from Chandigarh, India. Results of a t-test for equality of means showed no association of zygosity with any of the traits. Heterogeneity of total variance was found in 18 traits, which invalidates conventional genetic variance estimates and reveals considerable hidden environmental determinance. In contrast to other studies, Indian MZ twins had higher variance than did DZ twins, in most instances. There was also evidence of stronger environmental covariance for MZ and DZ twins. The study revealed substantial, complex environmental determination for some dental dimensions, especially of incisors and second molars.

Protein turnover in the cytoplasmic transport system within an insect ovary--a clue to the mechanism of microtubule-associated transport

The movement of radioactively labelled polypeptides into the microtubule-associated transport channels in the ovaries of a hemipteran insect has been analysed using SDS-polyacrylamide slab gel electrophoresis and fluorography. The patterns of label suggest that the microtubules which pack the transport channels form a relatively static cytoskeleton while other components move independently from them along the channels. As well as illustrating the functional organisation of microtubule-associated transport in this system our studies of labelled proteins have also provided clues as to the mechanism of transport itself.

Familial resemblance for head size in a Punjabi population of India

Four head measurements were taken on a sample of 45 MZ and 101 DZ twin pairs, their 125 singleton siblings, 104 fathers and 103 mothers in 146 Punjabi families living in Chandiagarh, India. The data indicate stronger genetic determination for the gross head size than its different components. Apart from genetic factors the role of environmental factors in the transmission of these traits is discussed. No higher maternal effect in the transmission of these traits have been found in the present data. However, on the contrary a higher paternal effect is indicated. The heritability estimates from siblings and twin data are higher than those from parent-offspring data. The influence of dominance factors in the transmission of head height is also suggested.

Within- and between-zygosity variance in oral traits among US and Punjabi twins

Cross-cultural comparison of twin variances reveals widespread heterogeneity among zygosities for dental occlusal traits, implying various biases in calculation of genetic variance or heritability estimates. These estimates are fairly robust for dental size traits, however. Differences in pattern between Punjabi (Northwest Indian) and American twins highlight the environmental differences that affect heritability determinations.

A family study of anthropometric traits in a Punjabi community: II. An investigation of familial transmission

Path analysis is used to characterize family resemblance for anthropometrics in twins and nuclear families from the Punjabi population of India. Significant positive assortative mating exists with respect to many body measurements, but not for cranial or facial variables. Evidence of a maternal effect for five measurements of bone diameter is reported. Twin resemblance is increased by a component not found in other pairs of relatives for all variables except nasal height, facial length, ear length, and head breadth. Although all variables have significant transmissible components, many have parameter estimates which are not consistent with strictly polygenic inheritance. Some form of cultural transmission is implicated for such variables, especially for those related to fatness levels.

A family study of anthropometric traits in a Punjabi community: I. Introduction and familial correlations

Data on 40 anthropometric measurements from 144 nuclear families in Chandigarh, India, are presented. Most families contain a pair of monozygotic or dizygotic twins, one or more singleton siblings, and their parents. Familial correlations for age-sex standardized, normalized measurements are estimated by maximum likelihood for marital, parent-child, sibling, and twin pairs. Heterogeneity tests for sex-specific subtype correlations male-male, male-female, female-female) indicate that the sex of the relative plays no significant role in the magnitude of the familial correlations except for maternal effects and differences among male and female twin pairs for a few of the variables. Marital correlations are high for body measurements, but not for head or face variables. Twin correlations seem to indicate a higher level of heritability than correlations from other family members.

Commingling in the distributions of fat-related measures in Punjabi families

The distribution of anthropometric measurements related to fatness levels is examined to determine if skewness alone accounts for the nonnormality of such measures. A mixture of two normal distributions or a single skewed distribution fit the data significantly better than a single normal in all cases. For maximum hip width, knee diameter, and weight, two skewed distributions give a better fit than one skewed distribution, rejecting the null hypothesis of a single distribution even when skewness is considered. There is evidence for three skewed component distributions for biceps skinfold. Abdomen circumference, upper arm circumference, triceps skinfold, and calf skinfold are best approximated by a one component log-normal distribution. Children and parents show slightly different patterns in skewness and kurtosis when considered separately, but differences between them do not account for the commingling found in the combined distributions.

Susceptibility to motion sickness

A sample of 119 pairs of twins, together with their 87 siblings and 100 pairs of parents, were examined with respect to susceptibility to the motion sickness syndrome. Children were found to exhibit resistance to the syndrome below two years of age, and females were more susceptible than males. The incidence appeared to be highest in families with both parents affected. Concordance rates were much higher in MZ (100%) than in DZ pairs (27.6%). Genetic effects are likely, but cultural factors should not be ignored.

Mercury induced haematological and biochemical anomalies in Ophiocephalus (Channa) punctatus

The effect of LC50 (1.8 mg/l) and a sublethal (0.3 mg/l) concentration of mercuric chloride on the blood of a teleost fish, Ophiocephalus (Channa) punctatus (the freshwater murrel-soley) was observed at 96 h and 15 and 30 days. Haemoglobin and haematocrit decreased after exposure, but no marked alteration was observed in total plasma protein. Glucose, cholesterol, urea, sodium, chloride, calcium and phosphate increased after acute and chronic exposures. Glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase and amylase activities increased after exposure to LC50 for 96 h and to the sublethal concentration for 15 and 30 days. No marked alteration was observed in acid phosphatase activity. Alkaline phosphatase activity decreased in acute exposure, and increased in chronic exposure. Cholinesterase activity decreased after both acute and chronic exposures.