A craniometric study of bicoronal craniosynostosis (BCC).

We compared 20 cases of bicoronal craniosyntosis (BCC) using the linear and angular values of the normal statistical material for the same age and sex. The skull in BCC is significantly shortened and flattened but with normal width. The height of the frontal arch (FNBR) is significantly decreased. The base of the skull is depressed with angle AB2 significantly increased, and angle NTNO significantly decreased and, even in some cases, with negative angular values. This is inducing a sinking of LEA (length from N to T), and in some cases LEA is lower than the line LNO (distance from N to O). The cephalic index (CI) was significantly increased, and the calculated cranial capacity (CC) was significantly decreased. Bregma (BR) is moving anteriorly in BCC, inducing an anterior movement of the calvaria with a bulge around BR. In this anterior movement we designate lack of positive occipital rotation. In BCC there is an evident lack of positive occipital rotation. Superimposing our drawings on the reference line NBA, we found for the first time a movement of anatomical landmarks similar to that observed in the negative occipital rotation in vestibular orientation.     

A craniometric study of the black and white Colobus Illiger 1811 (Primates: Ceropithecoidea).

This study examines the craniometry of Black and White Colobus monkeys using 1072 specimens representing all the recognized subspecies (after Rahm, '70) of the genus. Seventy-six measurements were taken on each individual, and examined using canonical variates analysis and clustering by Ward's Error Sum method. The assumptions of the analytical techniques are shown to be met, and the results demonstrated to be stable. Examination of the populations for statistical difference and taxonomic distinctiveness using a multivariate extension of Mayr's Rule indicates that the taxonomy presented by Rahm ('70) is essentially correct, except that the subspecies of guereza across the northern part of Central Africa should be lumped into a single group--C. g. occidentalis--and the subspecies of montane angolan colobus in Eastern Zaire should all be lumped into C. a. ruwenzorii. The systematic patterns of the genus illustrate the whole range of the process of speciation, from barely distinct subspecies, to subspecies almost as distinct as allopatric species of the genus, and on the fully sympatric species Three major zoogeographic areas may be delineated: an East African area dominated by the effects of the Rift Valley, with a large number of subspecies isolated in forest islands; a Central African area with little subspeciation and sympatric overlap of the major species of Colobus; and a West African area with a clinal pattern of distribution of subspecies, and secondary intergradation. The arbitrary nature of Mary's Rule is also apparent. Lastly, the CVA indicated major differences across the genus to be located in the teeth and jaws, suggesting diet might be an important distinguishing feature in Colobus.     

A craniometric study of the C. de Lange syndrome (CdLS)

After a short review of our method, we compared the results of the radiographs of 18 cases of CdLS to the results of our normal material. All of our normal statistical data was obtained from AP and lateral view radiographs at a distance of 1 m, in the prevailing conditions of everyday practice in a radiological department. We studied quantitative changes such as microcephaly and brachycephaly, and for the first time we introduced qualitative changes such as occipital rotation and the study of obliquity of the foramen magnum (line BAO). We found microcephaly in all our cases of CdLS and brachycephaly in only 72%. Furthermore, we found a lack of positive occipital rotation in all our cases of CdLS and the line BAO turned posteriorly with O higher than BA. The same conditions were observed on our normal material only in an early postnatal stage.     

Differential activation of canonical Wnt signaling determines cranial sutures fate: A novel mechanism for sagittal suture craniosynostosis

Premature closure of cranial sutures, which serve as growth centers for the skull vault, result in craniosynostosis. In the mouse posterior frontal (PF) suture closes by endochondral ossification, whereas sagittal (SAG) remain patent life time, although both are neural crest tissue derived. We therefore, investigated why cranial sutures of same tissue origin adopt a different fate. We demonstrated that closure of the PF suture is tightly regulated by canonical Wnt signaling, whereas patency of the SAG suture is achieved by constantly activated canonical Wnt signaling. Importantly, the fate of PF and SAG sutures can be reversed by manipulating Wnt signaling. Continuous activation of canonical Wnt signaling in the PF suture inhibits endochondral ossification and therefore, suture closure, In contrast, inhibition of canonical Wnt signaling in the SAG suture, upon treatment with Wnt antagonists results in endochondral ossification and suture closure. Thus, inhibition of canonical Wnt signaling in the SAG suture phenocopies craniosynostosis. Moreover, mice haploinsufficient for Twist1, a target gene of canonical Wnt signaling which inhibits chondrogenesis, have sagittal craniosynostosis. We propose that regulation of canonical Wnt signaling is of crucial importance during the physiological patterning of PF and SAG sutures. Importantly, dysregulation of this pathway may lead to craniosynostosis.     

A study of maturation events in jackbeans (Canavalia ensiformis).

Changes in cell volume and 42K+ efflux associated with concentrative alanine uptake were studied in isolated rat hepatocytes suspended in Krebs-Ringer bicarbonate buffer. After addition of 10 mM-alanine, cellular water volume increased by 15% and the rate constant of 42K+ efflux by 250%. Alanine-induced 42K+ efflux was abolished by quinine and was strongly decreased when the cell-volume increase was counteracted by sucrose. The results suggest that K+ efflux during alanine uptake is implicated in a volume-regulatory response.     

A craniometric perspective on the transition to agriculture in Europe

Debates surrounding the nature of the Neolithic demographic transition in Europe have historically centered on two opposing models: a "demic" diffusion model whereby incoming farmers from the Near East and Anatolia effectively replaced or completely assimilated indigenous Mesolithic foraging communities, and an "indigenist" model resting on the assumption that ideas relating to agriculture and animal domestication diffused from the Near East but with little or no gene flow. The extreme versions of these dichotomous models were heavily contested primarily on the basis of archeological and modern genetic data. However, in recent years a growing acceptance has arisen of the likelihood that both processes were ongoing throughout the Neolithic transition and that a more complex, regional approach is required to fully understand the change from a foraging to a primarily agricultural mode of subsistence in Europe. Craniometric data were particularly useful for testing these more complex scenarios, as they can reliably be employed as a proxy for the genetic relationships among Mesolithic and Neolithic populations. In contrast, modern genetic data assume that modern European populations accurately reflect the genetic structure of Europe at the time of the Neolithic transition, while ancient DNA data are still not geographically or temporally detailed enough to test continent-wide processes. Here, with particular emphasis on the role of craniometric analyses, we review the current state of knowledge regarding the cultural and biological nature of the Neolithic transition in Europe.     

Hepatectomy in rainbow trout (Salmo gairdneri). A preliminary study

1. Partial hepatectomy (25% of liver mass removed) has been performed on rainbow trout using a procedure allowing a high level of survival. 2. The liver regeneration was complete from the point of view of liver weight, at the 30th post-operative day. 3. During the first weeks after surgery, the NH-excretion rate in both hepatectomized and shamoperated trout was higher than in intact controls. Likewise, the food intake was lower in the operated animals. 4. Both facts can be attribute to the stress situation caused by the surgical manipulations rather than the removal of the liver.     

Structure of poly d(A).poly d(T).

On the basis of the x-ray data from polycrystalline and well oriented fibers of the sodium salt of poly d(A).poly d(T) (Arnott et al, Nucl. Acids Res. 11, 4141-4155 (1983), a revised B'-DNA model incorporating B-like adenine and thymine strands is shown to give a much better x-ray agreement (R = 0.25) than the previously assigned model consisting of mixed sugar conformations in the two strands. The narrowing of the minor and the widening of the major grooves are promiscuous features of B'-DNA, which are common to all poly d(purine).poly d(pyrimidine) duplexes with two hydrogen bonded base-pairs and are in marked contrast with classical B-DNA. Due to modest propeller (-15 degrees), the cross strand diagonal hydrogen bonds (0.37 nm) in this duplex are not as strong as those in A,T-rich oligonucleotide crystal structures.     

Multivariate apportionment of global human craniometric diversity

Extensive research in human genetics on presumably neutral loci has shown that the overwhelming majority of human diversity is found among individuals within local populations. Previous apportionments of craniometric diversity are similar to these genetic apportionments, implying that interregionally differing selection pressures have played a limited role in producing contemporary human cranial diversity. Here we show that when cranial variation is independently partitioned using principal components analysis of Mosimann shape variables, some estimates of interregional craniometric differentiation are larger than those for most genetic loci. These estimates are similar to estimates for genetic loci where interregionally differing selection pressures are implicated in producing the observed patterns of variation within and among regions. These results suggest that differences among regions in at least some cranial features, particularly in the nasal region, are in part the product of interregionally differing selection pressures. Moreover, these results have implications for assessing the biological affinities of prehistoric samples that are temporally separated from contemporary human reference populations.     

Maximum likelihood estimation of human craniometric heritabilities

This study presents univariate narrow-sense heritability estimates for 33 common craniometric dimensions, calculated using the maximum likelihood variance components method on a skeletal sample of 298 pedigreed individuals from Hallstatt, Austria. Quantitative genetic studies that use skeletal cranial measurements as a basis for inferring microevolutionary processes in human populations usually employ heritability estimates to represent the genetic variance of the population. The heritabilities used are often problematic: most come from studies of living humans, and/or they were calculated using statistical techniques or assumptions violated by human groups. Most bilateral breadth measures in the current study show low heritability estimates, while cranial length and height measures have heritability values ranging between 0.102-0.729. There appear to be differences between the heritabilities calculated from crania and those from anthropometric studies of living humans, suggesting that the use of the latter in quantitative genetic models of skeletal data may be inappropriate. The univariate skeletal heritability estimates seem to group into distinct regions of the cranium, based on their relative values. The most salient group of measurements is for the midfacial/orbital region, with a number of measures showing heritabilities less than 0.30. Several possible reasons behind this pattern are examined. Given the fact that heritabilities calculated on one population should not be applied to others, suggestions are made for the use of the data presented.     

A karyological study of nine species of Torymus (Hymenoptera: Torymidae).

Haploid karyotypes composed of 5 metacentrics (T. umbilicatus, T. koebelei), 4 metacentrics plus 2 telocentrics (T. tubicola), 5 metacentrics plus 1 telocentric (T. warreni), 5 metacentrics plus 1 acrocentric (T. baccharidis, T. vesiculi, T. occidentalis, T. capillaceus), and 6 metacentrics (T. californicus) are described. Five metacentrics are postulated as ancestral for the Torymidae, based on karyotype frequency for the family and Robertsonian relationships among taxa. Karyotypes of 5 metacentrics plus 1 telocentric are considered ancestral for the genus Torymus. Derived karyotypes have apparently evolved independently in several lineages within the genus.     

A molecular mechanical study of the structure of poly(alpha-aminoisobutyric acid).

A molecular mechanical study has been carried out to determine the most favorable conformation of poly(Aib) both in solution and in the solid state. An energetic approach to the packing has been carried out by studying the stability of pairs of poly(Aib) chains. The study reveals a higher stability of a 3(10)-helix when forming part of a dimer whereas in isolated molecules the alpha-helix structure seems to be more stable depending on the length of the chain and dielectric constant of the environment.