Retrotransposon-related DNA sequences in the centromeres of grass chromosomes

Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.     

Cardiac startle and orienting responses in the great apes.

An investigation of cardiac patterns of startle and orienting in response to auditory and vibrotactile stimuli in 3 infant chimpanzees and 1 gorilla revealed cardiac acceleration in response to the initial presentations of stimuli of either modality. Cardiac acceleration was subject to rapid habituation and replaced on subsequent trials by cardiac deceleration. Results from chimpanzees and the gorilla were similar, although a slower rate of habituation was apparent in the gorilla. Findings are consistent with those obtained from humans and monkeys. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inferential reasoning by exclusion in great apes, lesser apes, and spider monkeys.

Using the cups task, in which subjects are presented with limited visual or auditory information that can be used to deduce the location of a hidden reward, Call (2004) found prima facie evidence of inferential reasoning by exclusion in several great ape species. One bonobo (Pan paniscus) and two gorillas (Gorilla gorilla) appeared to make such inferences in both the visual and auditory domains. However, common chimpanzees (Pan troglodytes) were successful only in the visual domain, and Bornean orangutans (Pongo pygmaeus) in neither. The present research built on this paradigm, and Experiment 1 yielded prima facie evidence of inference by exclusion in both domains for two common chimpanzees, and in the visual domain for two Sumatran orangutans (Pongo abelii). Experiments 2 and 3 demonstrated that two specific associative learning explanations could not readily account for these results. Because an important focus of the program of research was to assess the cognitive capacities of lesser apes (family Hylobatidae), we modified Call's original procedures to better suit their attentional and dispositional characteristics. In Experiment 1, testing was also attempted with three gibbon genera (Symphalangus, Nomascus, Hylobates), but none of the subjects completed the standard task. Further testing of three siamangs (Symphalangus syndactylus) and a spider monkey (Ateles geoffroyi) using a faster method yielded prima facie evidence of inferential reasoning by exclusion in the visual domain among the siamangs (Experiment 4). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Alphoid repetitive DNA in human chromosomes

The thesis describes the first extensive DNA sequence analysis that demonstrated that the tandemly repeated alphoid DNA in the centromere of the human chromosomes consists of distinct subfamilies and in a number equal to or exceeding the number of chromosomes. The expected presence of only one or a few distinct subfamily on individual chromosomes was supported by the characterization of an extremely well-defined subfamily specific for chromosome 7 and represented in the original collection of subfamilies. The pattern of chromosome-specificity breaks down among the acrocentric chromosomes where chromosomes 13 and 21 were found to share one and chromosomes 14 and 22 to share another specific subfamily. By in situ hybridization these subfamilies were shown not to be shared by other chromosomes. The remarkable pairwise pattern of sequence homogenization was present also in the chimpanzee genome raising the question of its biological role. However, the subfamilies on these human and chimpanzee chromosomes are not orthologous but were shown to originate from two evolutionarily different repeat families. It follows that dramatic sequence evolution has occurred in one or both species during or after separation. The sequence evolution might even occur at a higher rate in humans. This possibility was studied in orthologous alphoid sequences on the X chromosome of humans and the great apes. The analysis supports the general view that our closest relative is the chimpanzee and indicates that the rate of recombination is increased in the human repeat DNA. A "molecular clock" running faster in this DNA may have evolutionary implications. Finally, the usefulness of alphoid subfamilies as chromosome-specific markers is illustrated in a cytogenetic dissection of the centromeric region of Robertsonian translocations. The breakpoints were located to satellite III DNA leaving these chromosomes dicentric. The order of the different tandem DNAs on the p-arm of the acrocentric chromosomes could also be established.     

Regional localization of human M-BCR gene to chromosome 23 band q11 in the great apes

Cassettes based on a hisG-URA3-hisG insert have been modified by the addition of an KmR-encoding gene and flanking polylinker sites, greatly simplifying construction of gene disruption vectors in Escherichia coli. After gene disruption in yeast, URA3 can then be excised by recombination between the hisG repeats flanking the gene, permitting reuse of the URA3 marker.     

Comparative and familial analysis of handedness in great apes.

Historically, population-level handedness has been considered a hallmark of human evolution. Whether nonhuman primates exhibit population-level handedness remains a topic of considerable debate. This paper summarizes published data on handedness in great apes. Comparative analysis indicated that chimpanzees and bonobos show population-level right handedness, whereas gorillas and orangutans do not. All ape species showed evidence of population-level handedness when considering specific tasks. Familial analyses in chimpanzees indicated that offspring and maternal (but not paternal) handedness was significantly positively correlated, but this finding was contingent upon the classification criteria used to evaluate hand preference. Overall, the proportion of right handedness is lower in great apes compared with humans, and various methodological and theoretical explanations for this discrepancy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in the sciatic notch of great apes and modern humans

The sciatic notch has been widely used as a sexing criterion in modern humans. In order to better understand the sex differences of this feature in modern humans and great apes, four measurements of the sciatic notch were taken on samples of modern humans and great apes of known sex. Univariate (ANOVA) analysis and discriminant function analysis were performed on the extant taxa to determine: (1) the discriminating power of each variable in these samples of known group membership; and (2) which of these extant taxa shows the best discrimination between the sexes for the sciatic notch. Of the four extant taxa, the sciatic notch of Homo sapiens is the most sexually dimorphic, followed by Gorilla gorilla, and more weakly by Pongo pygmaeus, while Pan troglodytes is the least dimorphic of these taxa. Since the presence of a well defined sciatic notch is a hominid trait resulting from the dorsal extension of the posterior ilium, the close approximation of the sacrum to the acetabulum, the shortened ischium, and the accentuation of the ischial spine as part of the bipedal adaptation, it seems likely that the configuration of the sciatic notch in hominids was initially related to bipedalism, not reproduction. The development of sex differences in the sciatic notch of modern humans is more likely to have occurred after the transition to bipedality.     

Fluorescene in situ hybridization establishes homology between human and silvered leaf monkey chromosomes, reveals reciprocal translocations between chromosomes homologous to human Y/5, 1/9, and 6/16, and delineates an X1X2Y1Y2/X1X1X2X2 sex-chromosome system

The adhesive core of the desmosome is composed of cadherin-like glycoproteins of 2 families, desmocollins and desmogleins. The desmosomal cadherins show distinct patterns of expression in adult epidermis, and we have suggested that the desmocollins have a functional role in regulating the differentiation and/or morphogenesis of that epithelium (North et al. [1996] Proc. Natl. Acad. Sci. USA 93:7701-7705.). To examine this hypothesis, we cloned murine desmocollins and examined the induction patterns of desmocollins 1 and 3 during skin and skin appendage development. Desmocollins 3 and 1 were first expressed in epidermis in highly regional patterns at embryonic days 13.0 and 13.5, respectively, and both were up-regulated in general body epidermis at day 14.5. At this stage, epidermis is undifferentiated and the desmocollins showed an unexpected expression pattern. However, by day 18.5 when skin had undergone terminal differentiation, desmocollin 1 and 3 expression resembled that found in the adult. Thus, the establishment of the adult pattern of desmocollin expression corresponds to the adult pattern of epidermal stratification. We suggest that it is the ratio of desmocollin 1 to desmocollin 3 expression at different levels in the epidermis that is fundamental in establishing this pattern of differentiation.     

Interspecies comparative genome hybridization and interspecies representational difference analysis reveal gross DNA differences between humans and great apes

Comparative chromosome G-/R-banding, comparative gene mapping and chromosome painting techniques have demonstrated that only few chromosomal rearrangements occurred during great ape and human evolution. Interspecies comparative genome hybridization (CGH), used here in this study, between human, gorilla and pygmy chimpanzee revealed species-specific regions in all three species. In contrast to the human, a far more complex distribution of species-specific blocks was detected with CGH in gorilla and pygmy chimpanzee. Most of these blocks coincide with already described heterochromatic regions on gorilla and chimpanzee chromosomes. Representational difference analysis (RDA) was used to subtract the complex genome of gorilla against human in order to enrich gorilla-specific DNA sequences. Gorilla-specific clones isolated with this technique revealed a 32-bp repeat unit. These clones were mapped by fluorescence in situ hybridization (FISH) to the telomeric regions of gorilla chromosomes that had been shown by interspecies CGH to contain species-specific sequences.     

Recent discoveries of Dryopithecus shed new light on evolution of great apes

The origin and early evolution of the great ape/human clade (Hominidae) is currently a subject of debate. The controversy is fuelled by the fragmentary nature of the fossils which renders it difficult to determine clearly derived features that permit the recognition of fossil members of this clade. We report here the recent discovery of a facial skeleton and a temporal fragment with the petrosal bone of Dryopithecus laietanus, which provides a way out of an impasse. The lack of the fossa subarcuata is a great ape and human clade synapomorphy, and proves unequivocally that Dryopithecus belongs to this clade. The zygomatic possesses derived characters which reveal that Dryopithecus is related to the Ponginae and not to the African apes/humans, as recently suggested. The remaining morphological features are plesiomorphic and thus provide a good model of a common ancestor of all Hominidae.     

Environmental models and mental modes: Representational processes in the great apes and man.

Argues that psychologists are interested principally in those behaviors that imply some type of functional image or representation of the environment. When man's categories of experience are imposed on the great apes, solid evidence of correspondence between their construction of reality and our own is obtained. Their sensory capacities are similar, and they spontaneously classify their experiences with objects in ways that resemble those of man. These analytic dispositions are complemented by the ability to synthesize heterogeneous attributes as different properties of the same "object." It is clear that the unwelten of ape and man are similar in many respects. Although it is true that the contrast between ape and man seems greatest in the ability for creative reconstruction of experience--to display foresight, to imagine, to plan ahead--even here the differences may be more in degree than in kind. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human artificial chromosomes generated by modification of a yeast artificial chromosome containing both human alpha satellite and single-copy DNA sequences

A human artificial chromosome (HAC) vector was constructed from a 1-Mb yeast artificial chromosome (YAC) that was selected based on its size from among several YACs identified by screening a randomly chosen subset of the Centre d'Etude du Polymorphisme Humain (CEPH) (Paris) YAC library with a degenerate alpha satellite probe. This YAC, which also included non-alpha satellite DNA, was modified to contain human telomeric DNA and a putative origin of replication from the human beta-globin locus. The resultant HAC vector was introduced into human cells by lipid-mediated DNA transfection, and HACs were identified that bound the active kinetochore protein CENP-E and were mitotically stable in the absence of selection for at least 100 generations. Microdissected HACs used as fluorescence in situ hybridization probes localized to the HAC itself and not to the arms of any endogenous human chromosomes, suggesting that the HAC was not formed by telomere fragmentation. Our ability to manipulate the HAC vector by recombinant genetic methods should allow us to further define the elements necessary for mammalian chromosome function.     

Comparative study of the genomic organization of DNA repeats within the 5''-flanking region of the natural resistance-associated macrophage protein gene (NRAMP1) between humans and great apes

CONTEXT: Use of the quadrivalent meningococcal vaccine for control of outbreaks has increased in recent years, but the efficacy of meningococcal vaccine during mass vaccination campaigns in US civilian populations has not been assessed. OBJECTIVES: To evaluate the efficacy of the quadrivalent meningococcal vaccine against serogroup C meningococcal disease in a community outbreak setting and to evaluate potentially modifiable barriers to vaccination in an area with persistent meningococcal disease following immunization. DESIGN: Matched case-control study of vaccine efficacy using cases of serogroup C meningococcal disease in persons eligible for vaccination during mass vaccination campaigns. Control patients were matched by neighborhood and age. The control group was used to identify possible barriers to vaccination. SETTING: Gregg County, Texas, population 106076, from 1993 to 1995. PARTICIPANTS: A total of 17 case patients with serogroup C meningococcal disease eligible for vaccine and 84 control patients. MAIN OUTCOME MEASURES: Vaccine efficacy and risk factors associated with nonvaccination. RESULTS: Vaccine efficacy among 2- to 29-year-olds was 85% (95% confidence interval, 27%-97%) and did not change in bivariate analyses with other risk factors that were significant in univariate analysis. Among control patients, older age was strongly associated with nonvaccination; vaccination rates for 2- to 4-year-olds, 5- to 18-year-olds, and 19- to 29-year-olds were 67%, 48%, and 20%, respectively (chi2 for linear trend, P=.01). CONCLUSIONS: The meningococcal polysaccharide vaccine was effective against serogroup C meningococcal disease in this community outbreak. Although specific barriers to vaccination were not identified, older age was a risk factor for nonvaccination in the target population of 2- to 29-year-olds. In future outbreaks, emphasis should be placed on achieving high vaccination coverage, with special efforts to vaccinate young adults.     

Orthologous DNA sequence variation among 5S ribosomal RNA gene spacer sequences on homoeologous chromosomes 1B, 1D, and 1R of wheat and rye

5S ribosomal gene spacer sequences from the short-spacer arrays of wheat and rye were isolated by PCR. The 29 new DNA sequences displayed noticeable heterogeneity at scattered positions. Nevertheless, based on shared DNA sequence polymorphisms, sequence alignment clearly classified the sequences into three groups. Group-specific primer sets were designed to allow chromosomal assignment by PCR on nullitetrasomic wheat stocks, as well as on wheat-rye translocation and addition lines. The three groups were assigned to orthologous loci 5S-Rrna-B1, 5S-Rrna-D1, and 5S-Rrna-R1 on homoeologous chromosomes 1B, 1D, and 1R, respectively. Hence, group-specific DNA sequence variation could be related to fixed orthologous DNA sequence variation between 5S rRNA multigene families on the homoeologous group 1 chromosomes. In addition, members of the three groups showed fixed orthologous length polymorphism. Four sequenced 5S-Rrna-B1 units, however, had a duplication in the gene encoding region and are probably representatives of a nontranscribed subfamily of 5S rDNA repeating units. The observed chromosome-specific polymorphisms among sequences belonging to a multigene family with thousands of copies suggests that this type of polymorphism may exist in many genes and gene families in polyploid wheats. The implication of this finding in relation to the construction of molecular tools for wheat-genome analysis and manipulation is discussed.     

A new region of conservation is defined between human and mouse X chromosomes

Comparative mapping of the X chromosome in eutherian mammals has revealed distinct regions of conservation as well as evolutionary rearrangements between human and mouse. Recently, we and others mapped the murine homologue of CLCN4 (Chloride channel 4) to band F4 of the X chromosome in Mus spretus but to chromosome 7 in laboratory strains. We now report the mapping of the murine homologues of APXL (Apical protein Xenopus laevis-like) and OA1 (Ocular albinism type I), two genes that are located on the human X chromosome at band p22. 3 and in close proximity to CLCN4. Interestingly, Oa1 and Apxl map to bands F2-F3 in both M. spretus and the laboratory strain C57BL/6J, defining a new rearrangement between human and mouse X chromosomes.     

Frequent hypomethylation in Wilms tumors of pericentromeric DNA in chromosomes 1 and 16

RATIONALE AND OBJECTIVES: The purpose of this study was to test the effectiveness of resident-prepared, independent learning cases in teaching residents chest radiology. MATERIALS AND METHODS: Three 2nd-year residents (one each from the University of Wisconsin, the Oregon Health Sciences University, and the University of Michigan) prepared four chest radiology teaching cases each (total, 12 cases). Radiology residents from each institution were randomly divided into control (n = 30) and experimental (n = 35) groups. Residents from both groups took a pretest of 36 multiple-choice questions covering the material from the 12 teaching cases. Residents in the experimental group reviewed these cases independently, and both groups took the same test (posttest) immediately after the teaching cases had been reviewed and again 3 months later (final test). RESULTS: Test scores were similar across institutions (P > .05) but differed across time and treatment groups (experimental vs control) (P < .0001). Mean differences in test scores between the experimental and control groups at pretest, posttest, and final test were -0.4, +9.0, +4.0, respectively, demonstrating increased performance at posttesting that was still present (though somewhat attenuated) 3 months later at final testing. CONCLUSION: Independent study of resident-prepared chest radiology teaching cases increases the resident's knowledge for as long as 3 months after instruction.