Reconstruction of the STS 14 (Australopithecus africanus) pelvis

The study reports a reconstruction of the sacrum in STS 14 based on extrapolation from the measurements of the first two sacral vertebrae of STS 14 and of the angle formed by the anterior surfaces of their vertebral bodies. Reconstruction is based on comparisons of, and extrapolation from, sacra of Pan troglodytes, Homo sapiens, and Australopithecus afarensis. The reconstructed sacrum has an anterior sacral curvature of 39°. The two ossa coxae were also completed by mirror imaging of one side by the other. With the pelvis completely reconstructed, the pelvic dimensions for the antero-posterior (AP) diameters of the pelvic inlet, midpelvis, and pelvic outlet are 85, 68, and 69 mm and the corresponding transverse (TR) diameters are 109, 88, and 103 mm, respectively. The posterior sagittal diameters in the three pelvic planes are small compared to the anterior sagittal diameters. This analysis indicates that the STS 14 pelvis is platypelloid in the three pelvic planes; i.e., all the AP diameters are smaller than the corresponding TR diameters. This makes the STS 14 pelvis similar to that to Al 288-1, save for a less pronounced degree of platypelloidy at the inlet in the former. © 1995 Wiley-Liss, Inc.     

Variation in the pattern of cranial venous sinuses and hominid phylogeny

In 1967 Tobias noted that Australopithecus boisei cranium O.H.5 exhibited a cranial venous sinus pattern in which the occipital sinus and the marginal sinuses of the foramen magnum appeared to have replaced the transverse-sigmoid sinuses as the major venous outflow track. Specimens of A. robustus and several more recently recovered A. boisei crania also show evidence of enlarged occipital-marginal sinuses. In contrast, A. africanus and H. habilis retain a dominant transverse-sigmoid system that characterizes the great majority of extant apes and modern human cadaver samples. Pliocene A. afarensis exhibits a high frequency of occipital-marginal drainage systems. An examination of several series of precontact North American Indian crania shows that the frequency distribution of the occipital-marginal sinus pattern is spatiotemporally disjunct , ranging from 7.5% to 28%. The Late Pleistocene sample from P redmost , Czechoslovakia, also shows a very high incidence of occipital-marginal sinus patterns (approximately 45%). These observations suggest that occipital-marginal and transverse-sigmoid sinus patterns are adaptively equivalent character states. This conclusion is supported by the fact that enlarged occipital-marginal and transverse-sigmoid sinus systems often coexist on the same and/or contralateral sides of the head. It is well known that the frequencies of such adaptively neutral traits are often heavily influenced by population-specific epistatic interactions. The utilization of such traits in phylogenetic reconstruction entails a substantial risk of mistaking parallelism for synapomorphy . It is concluded that using functional-adaptive criteria in the definition of morphologic characters is a more reliable method to guide phylogeny reconstruction. In light of this, the distribution of venous sinus variants in Plio -Pleistocene hominids gives little or no basis for revising the phylogenetic scheme of Johanson and White (1979), or the functional-adaptive interpretation offered by White et al. (1981).     

Individual tooth macrowear pattern guides the reconstruction of Sts 52 (Australopithecus africanus) dental arches

The functional restoration of the occlusal relationship between maxillary and mandibular tooth rows is a major challenge in modern dentistry and maxillofacial surgery. Similar technical challenges are present in paleoanthropology when considering fragmented and deformed mandibular and maxillary fossils. Sts 52, an Australopithecus africanus specimen from Sterkfontein Member 4, represents a typical case where the original shape of the dental arches is no longer preserved. It includes a partial lower face (Sts 52a) and a fragmented mandible (Sts 52b), both incomplete and damaged to such an extent to thwart attempts at matching upper and lower dentitions. We show how the preserved macrowear pattern of the tooth crowns can be used to functionally reconstruct Sts 52's dental arches. High‐resolutiondental stone casts of Sts 52 maxillary and mandibular dentition were mounted and repositioned in a dental articulator. The occlusal relationship between antagonists was restored based on the analysis of the occlusal wear pattern of each preserved tooth, considering all dental contact movements represented in the occlusal compass. The reconstructed dental arches were three‐dimensional surface scanned and their occlusal kinematics tested in a simulation. The outcome of this contribution is the first functional restoration of A. africanus dental arches providing new morphometric data for specimen Sts 52. It is noteworthy that the method described in this case study might be applied to several other fossilspecimens. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

A uniquely modern human pattern of endocranial development. Insights from a new cranial reconstruction of the Neandertal newborn from Mezmaiskaya

The globular braincase of modern humans is distinct from all fossil human species, including our closest extinct relatives, the Neandertals. Such adult shape differences must ultimately be rooted in different developmental patterns, but it is unclear at which point during ontogeny these group characteristics emerge.Here we compared internal shape changes of the braincase from birth to adulthood in Neandertals (N = 10), modern humans (N = 62), and chimpanzees (N = 62). Incomplete fossil specimens, including the two Neandertal newborns from Le Moustier 2 and Mezmaiskaya, were reconstructed using reference-based estimation methods. We used 3D geometric morphometrics to statistically compare shapes of virtual endocasts extracted from computed-tomographic scans. Throughout the analysis, we kept track of possible uncertainties due to the missing data values and small fossil sample sizes.We find that some aspects of endocranial development are shared by the three species. However, in the first year of life, modern humans depart from this presumably ancestral pattern of development. Newborn Neandertals and newborn modern humans have elongated braincases, and similar endocranial volumes. During a ‘globularization-phase’ modern human endocasts change to the globular shape that is characteristic for Homo sapiens. This phase of early development is unique to modern humans, and absent from chimpanzees and Neandertals.Our results support the notion that Neandertals and modern humans reach comparable adult brain sizes via different developmental pathways. The differences between these two human groups are most prominent directly after birth, a critical phase for cognitive development.     

Enamel-dentine junction (EDJ) morphology distinguishes the lower molars of Australopithecus africanus and Paranthropus robustus

Tooth crown morphology plays a central role in hominin systematics, but the removal of the original outer enamel surface by dental attrition often eliminates from consideration the type of detailed crown morphology that has been shown to discriminate among hominin taxa. This reduces the size of samples available for study. The enamel-dentine junction (EDJ) is the developmental precursor and primary contributor to the morphology of the unworn outer enamel surface, and its morphology is only affected after considerable attrition. In this paper, we explore whether the form of the EDJ can be used to distinguish between the mandibular molars of two southern African fossil hominins: Paranthropus (or Australopithecus) robustus and Australopithecus africanus. After micro-computed tomographic scanning the molar sample, we made high-resolution images of the EDJ and used geometric morphometrics to compare EDJ shape differences between species, in addition to documenting metameric variation along the molar row within each species. Landmarks were collected along the marginal ridge that runs between adjacent dentine horns and around the circumference of the cervix. Our results suggest that the morphology of the EDJ can distinguish lower molars of these southern African hominins, and it can discriminate first, second, and third molars within each taxon. These results confirm previous findings that the EDJ preserves taxonomically valuable shape information in worn teeth. Mean differences in EDJ shape, in particular dentine horn height, crown height, and cervix shape, are more marked between adjacent molars within each taxon than for the same molar between the two taxa.     

The eruption pattern of the permanent incisors and first permanent molars in Australopithecus (Paranthropus) robustus

This study aims to reassess the claim that the eruption sequence of the permanent incisor and first permanent molar teeth of Australopithecus (Paranthropus) robustus is identical with that in modern Homo sapiens. Eight fossil hominid mandibles of equivalent dental developmental age were chosen for comparative study. Emphasis has been placed upon the comparative timing of events within the growth period rather than eruption sequence alone. The results of this study indicate that Homo sapiens and Australopithecus (Paranthropus) robustus share the same pattern of permanent molar and incisor eruption and that this is significantly different from the pattern of eruption shared by the great apes, Australopithecus africanus and Australopithecus afarensis.     

Morphofunctional reconstruction of the brain of <Emphasis Type="Italic">Paroxyaena pavlovi</Emphasis> (Hyaenodontidae,Creodonta) based on a natural endocranial cast

The study of a natural endocranial cast of Paroxyaena has shown that its vision was an important system of afferentation, but did not prevail over others, unlike that of Neohyaenodon. The olfaction was much better developed than in Neohyaenodon. The large gyrus prorealis suggests the presence of a long mobile nose. The well-developed sensomotoric cortex is evidence that the forepaw of Paroxyaena showed a high mobility.     

Evidence for the existence of a subsinus layer of the peripheral cortex in the lymph node of the rat

Summary The peripheral cortex of a lymph node consists of folliculo-nodules (follicles with a nodule or germinal center) and an extrafollicular zone. In the course of an analysis of the nodes in rats under various experimental or abnormal conditions, our attention became focused on the particularities of a thin layer of peripheral cortex underlying the subcapsular sinus. The present paper reports on observations which led to the identification of the subsinus layer of the peripheral cortex. The observations suggest that this layer complements the activity of the inner wall of the subcapsular sinus. The layer probably contributes to the selection of certain elements from the afferent lymph and guides them towards the node area where they can join the cell population involved in the immunological activity in which they are to participate.     

Evidence for a New Member of the Myosin I Family from Mammalian Brain

Myosin I is an actin-based motor responsible for powering a wide variety of motile activities in amebae and slime molds and has been found previously in vertebrates as the lateral bridges within intestinal epithelial cell microvilli. Although neurons exhibit extensive cellular and intracellular motility, including the production of ameboid-like growth cones during development, the proteins responsible for the motor in these processes are unknown. Here, we report the isolation of a partially purified protein fraction from bovine brain that is enriched for a 150-kDa protein; immunochemical and biochemical analyses suggest that this protein possesses a number of functional properties that have been ascribed to myosin I from various sources. These properties include an elevated K(+)-EDTA ATPase, a modest actin-activated Mg(2+)-ATPase, the ability to bind calmodulin, and a ready association with phospholipid vesicles made from phosphatidylserine, but not from phosphatidylcholine. The combination of these properties, together with a molecular mass of 150 kDa (most myosin I molecules found to date have molecular masses in the range 110-130 kDa) yet recognition by an anti-myosin I antibody, suggests the presence of a new member of the myosin I family within mammalian brain.     

Evidence for a coding pattern on the non-coding strand of the E. coli genome.

Analysis of codon usage frequency for the combined coding sequences of 52 E. coli genes, taken from the European Molecular Biology Laboratory Nucleotide Sequence Data Library, Release 2, shows that there is a significant positive correlation between the frequency with which a given codon appears on the coding strand and the frequency with which it appears, in phase, on the non-coding strand.     

Phosphoglucomutase-1 subtypes in the Albanian ethnic minority of the province of Cosenza (Calabria-Southern Italy): Presence of a new variant

Allele frequencies of the phosphoglucomutase-1 (PGM1), in the Albanian ethnic minority of province of Cosenza (Calabria-Southern Italy) were compared with the corresponding data from neighbouring non-Albanian sample groups. The isoelectrofocusing evaluation in the two populations revealed the presence of a new variant PGM1^*W31 in Albanian sample group. Furthermore, a significant heterogeneity was observed between Albanian allele frequencies and those of the surrounding groups.     

Evidence for a dual effect of dibutyryl cyclic AMP on the synthesis of tyrosine aminotransferase in rat liver

A single injection of dibutyryl cyclic AMP (Bt2cAMP) into adrenalectomized rats results in rapid and proportionate increases in hepatic tyrosine aminotransferase catalytic activity and in the amount of functional mRNA coding for this enzyme. This effect is transient in that mRNATAT peaks at 0.065% of total poly(A)+RNA activity at 1 h and is back to the basal level of 0.012% in 2.5 h. Enzyme activity peaks at 2.5 h and is back to the basal level by 5 h. If Bt2cAMP is repeatedly injected (0, 1, 2.5, and 4 h), enzyme activity remains at maximal levels for 4 to 5 h, whereas changes in mRNATAT activity are identical with those observed in the single injected rats. The rate of tyrosine aminotransferase synthesis at 5.5 h in the multiply injected rats, a time when mRNATAT has already returned to the basal level, is 3 to 4 times greater than that in either control or singly injected rats at the same time (0.3% of total protein versus 0.07%) and is equivalent to the maximal rate seen 1 h after the initial injection of the cyclic nucleotide. Since the rate of synthesis is increased in proportion to the increase in enzyme catalytic activity, stabilization of the enzyme against degradation is excluded as an induction mechanism at this late time point. These responses are not due to differences in the metabolism of Bt2cAMP, and the effect depends on the presence of metabolically active derivatives of this nucleotide. It thus appears that Bt2cAMP induces the synthesis of tyrosine aminotransferase in rat liver in two distinct ways. One is pretranslational and involves a transient and rapid increase in mRNATAT activity. The second appears to involve a delayed but sustained increase in translation of a basal level of mRNATAT.     

Evidence for the existence of a robust pattern of prey selection in food webs

Food webs aim to provide a thorough representation of the trophic interactions found in an ecosystem. The complexity of empirical food webs, however, is leading many ecologists to focus dynamic ecosystem studies on smaller microcosm or mesocosm studies based upon community modules, which comprise three to five species and the interactions likely to have ecological relevance. We provide here a structural counterpart to community modules. We investigate food-web 'motifs' which are n-species connected subgraphs found within the food web. Remarkably, we find that the over- and under-representation of three-species motifs in empirical food webs can be understood through comparison to a static food-web model, the niche model. Our result conclusively demonstrates that predation upon species with some 'characteristic' niche value is the prey selection mechanism consistent with the structural properties of empirical food webs.     

Effect of selection for behavior on the cranial traits of the American mink (Mustela vison)

Cranial sizes of American mink selected for tame and aggressive behavior (towards humans) and control mink, which were not selected for behavior, were compared. Absolute sizes of the skull were demonstrated to change depending on the direction of selection. Sexual dimorphism was reduced in mink selected for aggressive behavior, because the cranial sizes of females increased and those of males decreased. Cranial traits were analyzed by the method of principal components. The groups studied differed from one another with respect to the first four components. Although the vector of selection determined the differences between the groups, some morphological changes were similar in the groups selected for tame and aggressive behavior.     

Gm and Inv (Km) studies of melanesian people on the Huon Peninsula in northeast Papua New Guinea: Polymorphism for a Gm1,5,10,11,13,14,17,21,26 haplotype

Blood samples from 448 people living in six villages in the Huon Peninsula in northeast Papua, New Guinea, were tested for Gm(1,2,3,5,6,10,11,13,14,17,21,24,26) and Inv(1) [Km(1)]. All the people are non-Austronesian (NAN) speakers. As expected, there was a low frequency of the Gm^{1,3,5,10,11,13,14,26} haplotype, but in contradiction to expectations there was a complete absence of the Gm^1,2,17,21,26 haplotype. In addition, samples from people in one village (Yupna) and probably those for two other villages (Irumu 13 and 14) have the rare haplotype Gm^{1,5,10,11,13,14,21,26} at polymorphic frequencies. Two samples from people living in Yupna had the rare phenotype Gm(1,3,17,21,26), indicating the presence of any one of several rare haplotypes that had been observed in other populations. These are discussed.