The dark-colour-inducing neurohormone of locusts in relation to an albino mutant of Schistocerca gregaria

In the albino mutant of an Okinawa strain of Locusta migratoria (L.) (Orthoptera: Acrididae), albinism is caused by the absence of the dark‐colour‐inducing neurohormone (DCIN), which is present in the corpora cardiaca (CC) of normally coloured phenotypes. This study tests whether the absence of DCIN is responsible for albinism in an albino mutant of another locust, Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae). This seemed feasible because a single Mendelian unit controls albinism in both species. However, implantation of CC, or injection of an extract of CC, from albino donors of S. gregaria, induce dark coloration in crowded nymph recipients of the Okinawa albino mutant of L. migratoria, as effectively as do implanted CC, or injections of extract of CC, from normal phenotype donors of S. gregaria. Therefore, DCIN is present in the albino mutant of S. gregaria, and consequently, the albinism in this mutant is not caused by its absence. Implantation of CC, or injection of extracts of CC, from albino donors of S. gregaria to conspecific albino nymphs does not induce darkening. Only extremely high doses of synthetic DCIN injected into albino nymphs of S. gregaria are effective, inducing some darkening. The dose to induce such darkening in albino nymphs of S. gregaria is 50 nmol, ≈ 5 × 10⁶ times higher than that (10 femtomol) needed to induce equivalent darkening in nymphs of the Okinawa albinos of L. migratoria. The results are discussed and some possible explanations of the observed effects outlined.     

Ethnic and family factors of some common diseases in early childhood

The primary purpose of the present study was to examine the comparative incidence of some common diseases with unknown genetic components (e.g. newborn jaundice, urinary and respiratory tract infections) in infants of Israeli families of mixed and non-mixed ethnic origin. We also studied possible relationships between risk of these diseases and a number of anthropometric and demographic factors. Only the group of infants whose parents originated from North Africa and Middle East showed statistically significant differences: namely an increased level of total morbidity, of various comparisons of specific disease frequencies, and in total illness frequency, between infants from "mixed" and "non-mixed" families. In general, however, there was a positive correlation between frequency of healthy infants in "mixed" group and genetic distance between parents. Our findings also indicated a significant association between weight and head circumference of newborn infants respectively, and their illnesses, especially jaundice.     

Morphological traits and common illness in newborn infants

The present study focussed on neonates morbidity in connection with the morphological traits in the individual relative to the population average and in connection with the fluctuating asymmetry (FA) in 8 bilateral traits. The sample comprised two categories of newborn infants: 1) 1088 full term children, in which body weight (W), body height (H) and head circumference (HC) were measured on the day of birth; and 2) 216 infants of various gestation age (from 26 to 41 weeks) in which 6 measurements of upper and lower arm breadth, plus ear length and breadth on both sides of the body, were made during the first 72 hours of life. Relevant vital statistics were also obtained from parents. The following major categories of morbidity were observed in our samples: jaundice, respiratory diseases, cardiovascular diseases, urinary tract infections (only in the second sample), haematological diseases and ‘varia’. The results show that W, H, HC and W/H² index are significantly correlated with a predisposition to various categories of morbidity. For W and W/H² index, this correlation remains significant even after adjustment for diverse anthropometric and demographic variables. In the case of urinary tract infection, the contribution of HC also remains significant even after the adjustment procedure. Gestational age and cardiovascular illnesses yielded significant correlations with mean FA. There was an evident decrease in mean FA upon increase of gestational age. The mean FA of infants suffering from cardiovascular morbidity displays the same trend, although it is consistently higher compared to the total group of infants in the respective gestational age.     

Flexibility difference between double-stranded RNA and DNA as revealed by gel electrophoresis

A systematic study of agarose gel electrophoresis of double-stranded RNA in the kilobase range of sizes was performed. The dsRNA to dsDNA relative mobility was found to depend on gel concentration: in low density gels RNA moves slower and in high density gels - faster than DNA of the same molecular size. The electrophoretic differences were interpreted within the reptation theory to be mainly due to the molecular stiffness differences. The dsRNA persistence length was roughly estimated to be about twice as great as that of DNA.     

Conjugation transfer of the plasmid pAMbeta1 into various Bacillus species

Streptococcal broad host range plasmid pAM beta 1 was transferred by a conjugation-like process from Streptococcus faecalis to 13 strains of different Bacilli species. In intraspecies matings the frequencies of transfer of pAM beta 1 varied from 2.10(-5) to 1.10(-8). As it was shown by comparative analysis the frequency of transfer and stability of the maintainance of plasmid pAM beta 1 in Bacilli were not connected. Molecular weight and restriction pattern of pAM beta 1 DNA isolated from Bacilli were the same as those of pAM beta 1 DNA from Streptococcal donor strain.     

Variables affecting dental fluctuating asymmetry in human isolates

The aims of the present study are to 1) determine and describe levels of dental fluctuating asymmetry (FA) in a highly endogamous human group; 2) evaluate the effects of various FA measures on perceived FA levels and their interrelationships; 3) study the connections between dental variables (tooth size, class, position, type, location and dimension) and FA levels; and 4) estimate the interrelationships between dental FA measures. The study was carried out on 242 Bedouin boys aged 5 to 14 years. The results demonstrate that the main variables influencing dental FA levels within this population are tooth class (incisors, canine, premolars, molars) and position (mesial, distal) and that the interaction between the two is significant. When sample sizes are large enough and individual measures are needed for the statistical analysis, the use of a computational method based on absolute values is legitimate. Clear relationships between some FA dental traits are discerned though principal-components analysis. © 1993 Wiley-Liss, Inc.     

Survival,behaviour and spatial distribution of shell morphs in a population of the snail Brephulopsis bidens (Pulmonata)

Summary Microspatial variation of banded and unbanded shell morphs frequencies as well as number of individuals per m², mortality, migration and burrowing into the ground were examined in a population of snail Brephulopsis bidens found in South Crimea mountains (USSR). Differential values of relative survival of morphs were determined by their thermotolerance. The relative survival of the banded morph was lower at the west sites of population area (W=0.273), and increased gradually up to 1 at the east sites. Survival of the banded morph was dependent on its burrowing activity. Differences in relative survival of morphs decreased parallel with increasing general mortality of snails.Burrowing activity and intensity of migration of the banded morph were significantly higher than that in unbanded. In experiments with artificial shaded sections, the banded morph preferred shaded sections, whereas unbanded chose illuminated sites. All these differences in behaviour probably form the main factors for microspatial variation of morph frequencies.