Three-dimensional analysis of the maxillary first molar crowns of Canadian Inuit

The maxillary first molar crowns of 48 male and 38 female Canadian Inuit (Eskimos) were analyzed three-dimensionally by using moiré contourography methods. Cusp heights were significantly higher in males while the mesial and distal marginal ridges were more proximally placed in males. The metacone and the oblique ridge appeared to be better developed in the males. Comparison of the present results with published results for Dutch and Japanese indicated that the Japanese and Inuit had lower cusps that were more widely spaced than the Dutch. Correlation coefficients suggest that height measurements were positively correlated as were linear measurements. However, there were few significant correlations between height and linear determinations, suggesting that the development of the "width" of a crown is nearly independent of the development of the height of the cusps and crown.     

Shape components of the maxillary molars in Australian aboriginals

Principal components analysis was used to quantify the variability in crown outlines of maxillary molars in Australian Aboriginals. The outlines were measured by 36 radii from the central pit to the crown periphery. The first component, responsible for over half of the total variance, was concerned with general crown size. Four remaining components were retained to indicate sources of variability resulting from contrasting degrees of development or reduction of different crown components. Shape changes from the first to third molars were identified with components representing overall size reduction, diminution of the hypocone, and metacone elements and mesiodistal compression. An anteroposterior gradient along the molar series in average scores and variances for all components resulted from the progressive reduction of distal crown elements, increasing mesiodistal compression, and greater morphological variation.     

Comparative study of the upper molar occlusal table morphology among seven human populations

Three-dimensional morphology of the occlusal table of the upper first molars was compared in seven racial populations. Materials were moiré contourograms collected by ourselves over 5 years. Intercuspal distances and cuspal heights were comparatively studied in this analysis. When the populations were arranged in the order of these sizes, their arrangements based on intercuspal distances and cuspal heights were quite different from each other. When intercuspal distances were scaled by protocone-paracone distance, the distances connecting distal cusps were significantly smaller in Mongoloids (Japanese and Eskimo) than in Caucasoids (Dutch and Asiatic Indian), which suggests a reduction tendency of distal cusps in Mongoloids. This tendency was intermediate in Negroids and Australoid. Principal coordinate analysis was carried out on the basis of a similarity matrix including both intercuspal distances and cuspal heights. The result suggested that the three-dimensional shape of the occlusal table was distinguishable in four representative racial populations.     

Morpho-molecular analysis as a prognostic model for repulsive feedback of the medicinal plant “Andrographis paniculata” to allogamy

Andrographis paniculata Nees. (AP) is a self-pollinated medicinal herb with a wide range of pharmaceutical properties, facing a low diversity in Malaysia. Cross-pollination of AP accessions leads to considerable rates of heterosis in the agro-morphological characteristics and anticancer phytochemicals of this eminent medicinal herb. However, the poor crossability of the plant at the interpopulation or intraspecific levels is an obstacle from the evolutionary and breeding points of view as an average of 4.56% crossability was recorded for AP in this study. Hence, this research aimed to elicit the impact of parental genetic distances (GDs) on the rate of crossability of AP using seven accessions in 21 possible cross combinations. To this end, a set of 55 randomly amplified polymorphic DNA (RAPD) primers and a total of 13 agro-morphological markers were employed to test the hypothesis. Twenty-two out of the 55 RAPD primers amplified a total of 257 bands of which 107 bands were found to be polymorphic. The principal component analysis (PCA) based on the RAPD markers revealed that the studied AP accessions were distributed to three distinct groups. Furthermore, it was noticed that even a minor increase in GD between two parents can cause a decline in their crossability. Unlike, the morphological-based GDs acted neutrally to crossability. This finding suggests that, despite the low genetic diversity among the Malaysian APs, a population prescreening using RAPD markers would be useful to enhance the rate of fruit set through selecting the genetically adjacent parents.     

Intermonomer electron transfer in the bc1 complex dimer is controlled by the energized state and by impaired electron transfer between low and high potential hemes

The cytochrome bc(1) complex (commonly called Complex III) is the central enzyme of respiratory and photosynthetic electron transfer chains. X-ray structures have revealed the bc(1) complex to be a dimer, and show that the distance between low potential (b(L)) and high potential (b(H)) hemes, is similar to the distance between low potential hemes in different monomers. This suggests that electron transfer between monomers should occur at the level of the b(L) hemes. Here, we show that although the rate constant for b(L)-->b(L) electron transfer is substantial, it is slow compared to the forward rate from b(L) to b(H), and the intermonomer transfer only occurs after equilibration within the first monomer. The effective rate of intermonomer transfer is about 2-orders of magnitude slower than the direct intermonomer electron transfer.