The significance of pollination time and frequency and of purity of pollen loads for seed set in Rhinanthus angustifolius (Scrophulariaceae) and Viscaria vulgaris (Caryophyllaceae)

Summary The effects of time of the day and frequency of application and of purity of artificially deposited pollen loads on fruiting and seed set were studied in Rhinanthus angustifolius (diurnally visited by bumblebees) and Viscaria vulgaris (diurnally visited by bumblebees, nocturnally by sphingid moths).Time of the day did not influence pollination success in either species. Increase of pollination frequency increased fruiting and seed set in Rhinanthus but had no affect on Viscaria. Five successive artificial pollinations were needed to achieve seed set equal to that observed naturally in Rhinanthus while a single artificial pollination was sufficient in Viscaria. Mixing Lupinus and Viscaria pollen did not reduce fruiting and seed set in Viscaria. The results are discussed in relation to observed seed sets in early and late flowers, and small and large patches of Viscaria vulgaris and among Rhinanthus flowers in populations of different densities.     

Testing the success of palaeontological methods in the delimitation of clam shrimp (Crustacea,Branchiopoda) on extant species

Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species-diagnostic; seven ornamentation types are distinguished of which six are species-specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata.     

Skeletal Lesions in Human Tuberculosis May Sometimes Heal: An Aid to Palaeopathological Diagnoses

In three to five percent of active cases of tuberculosis, skeletal lesions develop. Typically, these occur on the vertebrae and are destructive in nature. In this paper, we examined cases of skeletal tuberculosis from a skeletal collection (Galler Collection) with focus on the manifestation of bony changes due to tuberculosis in various body regions in association with antibiotic introduction. This skeletal collection was created in 1925–1977 by a pathologist at the University Hospital in Zürich, Ernst Galler. It includes the remains of 2426 individuals with documented clinical histories as well as autopsies. It contained 29 cases of skeletal tuberculosis lesions. We observed natural healing of vertebral lesions through several processes including fusion of vertebrae, bone deposition and fusion of posterior elements. In these cases, we observed a higher frequency and proportion of bone deposition and fusion of posterior vertebral elements where pharmacological agents were used. There were also four cases of artificial healing through surgically induced posterior spinal fusion. With the introduction of pharmaceutical treatments, the number of individuals with multiple tuberculous foci decreased from 80% to 25% when compared to individuals who did not receive any drug therapy. Investigation of comorbidities showed that pneumonia, pleuritis and being underweight were consistently present, even with pharmaceutical treatment. Our results have applications in palaeopathological diagnoses where healing and consequent bone deposition may complicate differential diagnoses.     

Sexually dimorphic mandibular morphology in the first few years of life

Sex differences in the youngest skeletons are very subtle, and any method that can separate males and females significantly better than chance will be of value. Compounding the problem is a paucity of immature skeletons of documented age and sex. In 1992, S.R.L. examined 62 juvenile mandibles of white and black South Africans of known age and sex (from birth to 19 years) from the Dart Collection to determine if the sexes could be differentiated by morphologic traits. By age 6 years, adult chin shapes were already recognizable. Prior to that age, differences were observed in the shape of the inferior border of the symphysis and outline of the body. The male chin base extends steeply downward relative to the adjacent body, coming to a point or squaring off at the symphysis. In females, the symphysis descends gradually to a more rounded base, and even when pointed, the transition is not abrupt. On the outer border of the corpus, the sides diverge sharply to form a \_/ shape from a roughly horizontal anterior region in males, while the female contour is rounded, reflecting the smoothly curved transition from front to sides. These traits were manifest from the eruption of the central incisors until about 4 years of age. The features were tested on all 19 Dart Collection mandibles in that age range. Average accuracy for three different testers was 81%, and males were consistently identified more accurately than females. This new method was then tested on a known sex sample of 11 individuals from 0 to 7 years of age. These included CT scans of 9 French children and the remains of 2 South African black forensic cases. Sexing accuracy was 82% (9/11). The only two missexed cases were both female and over age 6 years. In conclusion, the results of this study indicate that it is possible to determine the sex of very young mandibles. The new sexually dimorphic morphologic configurations introduced here have demonstrated repeatable discrimination with the highest level of accuracy (81%) reported and tested for this age group. Preliminary research indicates that both the male and female shapes are clearly recognizable in archaeologic and premodern hominids as well as chimpanzees.     

Novel nuclear and mitochondrial glycosylases revealed by disruption of the mouse Nth1 gene encoding an endonuclease III homolog for repair of thymine glycols

Endonuclease III, encoded by nth in Escherichia coli, removes thymine glycols (Tg), a toxic oxidative DNA lesion. To determine the biological significance of this repair in mammals, we established a mouse model with mutated mNth1, a homolog of nth, by gene targeting. The homozygous mNth1 mutant mice showed no detectable phenotypical abnormality. Embryonic cells with or without wild-type mNth1 showed no difference in sensitivity to menadione or hydrogen peroxide. Tg produced in the mutant mouse liver DNA by X-ray irradiation disappeared with time, though more slowly than in the wild-type mouse. In extracts from mutant mouse liver, we found, instead of mNTH1 activity, at least two novel DNA glycosylase activities against Tg. One activity is significantly higher in the mutant than in wild-type mouse in mitochondria, while the other is another nuclear glycosylase for Tg. These results underscore the importance of base excision repair of Tg both in the nuclei and mitochondria in mammals.     

Phylogenetic relationships of human populations in sub-Saharan Africa

This study utilizes the GM/KM immunoglobulin allotype system to elucidate the phylogenetic relationships of sub-Saharan Africans. The importance of understanding the relatedness of these peoples stems from the sub-Saharan region being the possible birthplace of humans. Haplotype distributions were determined for 19 populations and compared using chi-square analysis. Published data of other sub-Saharan Africans and representative populations worldwide were also added for comparison. Genetic distances between populations were calculated based on haplotype frequencies, and genetic relationships were observed through principal components analysis. Data from the GM/KM system showed a genetic homogeneity of the Bantu populations, with some exceptions, supporting the possibility of a common origin of these peoples. The Malagasy appeared as a divergent population, most likely due to Southeast Asian/Austronesian admixture, as indicated by the presence of the GM*AF B haplotype. The Cape Coloured also showed a divergence, with their genetic structures containing Caucasoid and Khoisan contributions. Finally, the Mbuti Pygmies appeared genetically isolated and had the highest frequency of the GM*A B haplotype out of all studied populations.     

Ten years of life in compost: temporal and spatial variation of North German Caenorhabditis elegans populations

The nematode Caenorhabditis elegans is a central laboratory model system in almost all biological disciplines, yet its natural life history and population biology are largely unexplored. Such information is essential for in‐depth understanding of the nematode's biology because its natural ecology provides the context, in which its traits and the underlying molecular mechanisms evolved. We characterized natural phenotypic and genetic variation among North German C. elegans isolates. We used the unique opportunity to compare samples collected 10 years apart from the same compost heap and additionally included recent samples for this and a second site, collected across a 1.5‐year period. Our analysis revealed significant population genetic differentiation between locations, across the 10‐year time period, but for only one location a trend across the shorter time frame. Significant variation was similarly found for phenotypic traits of likely importance in nature, such as choice behavior and population growth in the presence of pathogens or naturally associated bacteria. Phenotypic variation was significantly influenced by C. elegans genotype, time of isolation, and sampling site. The here studied C. elegans isolates may provide a valuable, genetically variable resource for future dissection of naturally relevant gene functions.