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PubMed1999

Systematics and genetic structure of Ponderosae taxa (Pinaceae) inhabiting the mountain islands of the Southwest.

The systematics and genetic structure of taxa representing the Ponderosae subsection of genus Pinus were assessed for disjunct, isolated, and peripheral populations occupying the mountain islands of the Southwest. Wind-pollinated progenies of 290 trees were compared in common gardens according to ten variables reflecting allometric, needle, and phenologic characteristics of 2-yr-old trees. The tests also included populations of similar taxa from the Rocky Mountains to the north and the Sierra Madre to the south. Principal component and canonical discriminant analyses demonstrated that the taxa segregated into three distinct groups, one of which contained two subgroups. These groupings collectively accounted for all of the many and confusing taxonomic descriptions that exist for the Ponderosae of the southwest United States and northern Mexico. The results suggested that intertaxa hybrids or hybrid derivatives may have been segregating within the progenies of only three of the parental trees. Hybridization, therefore, appears to be infrequent and inconsequential to the interrelationships among taxa and to contemporary genetic structures of taxa. Univariate analyses showed that the three distinct groups displayed different genetic structures despite similarities in their geographic distributions. While genetic variation within populations of all groups was abundant, a group labeled "quinquefoliata" displayed little variation among populations; one labeled "engelmannii" had abundant interpopulation variation that was largely randomly distributed across the landscape; and in a group containing the subgroups called "scopulorum" and "taxon X," abundant interpopulation variability was arranged systematically along moderately steep clines. These disparate genetic structures showed no apparent effects of the isolated, disjunct, and peripheral conditions under which populations of these taxa exist.

Journal Article↗

PubMed1999

Conjugate ocular oscillations during shifts of the direction and depth of visual fixation.

PURPOSE: To characterize dynamic properties of combined saccade-vergence eye movements that occur as the point of visual fixation is shifted between objects lying in different directions and at different depths. METHODS: Using the scleral search-coil technique, eye movements were measured in 10 normal subjects as they made voluntary, disjunctive gaze shifts comprising a range of saccades and vergence movements. RESULTS: By analyzing eye acceleration records, the authors identified small-amplitude (0.2-0.7 degrees), high-frequency (23-33 Hz), conjugate horizontal oscillations of the eyes during the vergence movement that followed the initial saccade. When the shift of the fixation point required a large vergence component (17 degrees , every subject showed these oscillations; they were present in approximately a third of responses. Approximately 5% of responses showed oscillations that had horizontal and vertical components. Oscillations were less prominent with shifts that had smaller vergence components and were absent after saccades made between targets located at optical infinity. CONCLUSIONS: These findings suggest that a common mechanism gates both the saccadic and vergence components of disjunctive gaze shifts, a likely candidate being the pontine omnipause neurons. When a saccade is immediately followed by a prolonged vergence movement, the omnipause neurons remain silent, leading to small-amplitude saccadic oscillations. Shifts in the point of visual fixation that require a large vergence movement may be a useful experimental strategy to induce saccadic oscillations.

Adult↗

PubMed2000

Cytogenetic studies of 1001 Down syndrome cases from Andhra Pradesh, India.

Cytogenetic data obtained from investigating 1001 patients of Down syndrome (DS) and their parents over a period of 20 years (January 1979-January 1999) are presented. The frequency of pure trisomy, mosaicism and translocation was 87.92, 7.69 and 4.39 per cent respectively. The origin of the extra chromosome 21 due to meiotic non-disjunction was 79.24 per cent maternal and 20.76 per cent paternal. A high frequency of acrocentric chromosome associations was also observed in mothers of children of Down syndrome, this might have predisposed to an enhanced risk for non-disjunction. Birth order of DS showed a higher number of first and second borns. Reproductive performances of the parents indicated a high rate of abortions, compared to controls. Cytogenetic investigations carried out over these years greatly helped in the management of these children and for counseling the affected families.

Adolescent↗

PubMed2001

[Unstable pelvic ring fracture: osteosynthesis of the posterior lesion by percutaneous sacroiliac fixation].

PURPOSE OF THE STUDY: We report our experience with percutaneous sacroiliac screwing for unstable pelvic ring fracture. MATERIAL AND METHODS: Twenty unstable pelvic ring fractures with sacroiliac disjunction (9 cases), trans-sacral fracture (9 cases), or bilateral posterior fractures (5 cases) were managed with percutaneous sacroiliac fixation using 1 or 2 screws. There was also pubic disjunction in 7 cases, managed by osteosynthesis in 5 cases. No fixation of fractures of one or both of the obturator rings, present in 13 cases, was attempted. The posterior screwing was performed under fluoroscopic guidance in 15 cases and computed tomographic guidance in 5. RESULTS: There were no infectious or neurological complications. Radiographically, anatomic reduction of the posterior fracture was achieved in 10 cases. A vertical ascension persisted in 4 patients and a rotation in 6. Radiographic results were correlated with delay to surgery: correction of the vertical displacement was achieved in 80% of the patients operated before five days and in 55% of the others. Two patients experienced a secondary displacement. There was no cases of nonunion of either the anterior or posterior fracture. Follow-up was available for 14 patients (2 patients died and follow-up was too short for 4). The mean Majeed score was 92/100 and none of the patients experienced anterior pain. Three patients had moderate pain in the sacroiliac area. DISCUSSION: The ventral position appears to be best adapted for percutaneous sacroiliac screwing but can be contraindicated by concomitant lesions. We prefer fluoroscopic guidance for these emergency procedures. Two views, ascending and descending, appear sufficient. The better stability provided by two screws can be achieved under computed tomographic guidance without risk of neurovascular damage. CONCLUSION: Percutaneous sacroiliac screwing is a good management strategy for unstable pelvic ring fractures with little risk of morbidity.

Activities of Daily Living↗

PubMed2001

[Genetic screening of meiotic mutations in mosaic clones of the Drosophila melanogaster female germline].

A method of screening for meiotic mutations based on genetic analysis of chromosome disjunction in germline mosaic clones of females homozygous for potential mutations is proposed. The clones are obtained at high frequency due to the use of the transgenic FLP/FRT system of mitotic recombination. This system permits obtaining homozygous clones in the first generation after mutagenesis, whereas the cultures are set up after selection for potential meiotic mutations. This significantly enhances, the efficiency of screening by the elimination of the limiting stage. Using this method, the following mutations were revealed in the 3L arm of Drosophila: ff6 leading to disturbed centriole disjunction, which results in appearance of multi-tail spermatids and three-pole spindles during male meiosis; ff3 leading to the formation of chromosome bridges in anaphase and telophase, chromosome nondisjunction, and premature chromatin condensation after metaphase; embryonic lethal ff29, with disturbed coordination between nuclear and centrosome cycles during syncytial cleavage; and a series of other mutations causing a wide spectrum of disturbances in male meiosis. Comparison of the proposed method with procedures of screening for yeast cell-cycle mutations showed that we succeeded in attaining the efficiency of screening in the Drosophila model close to that in the yeast model.

Animals↗

PubMed1975

[Migration of glial cells in the brains of intact mice and mice with brain injuries during the first hours after DNA synthesis and cell division].

The behaviour of labelled (3H-thymidine) glial cells was studied in the brain of intact mice and mice with mechanical trauma of brain. Formation of pairs of labelled cells and their subsequent disjunction in the brain regions under study occurs at different rates. The rates of these processes in white matter and subependymal zone exceed those in parietal cortex, thalamus and hypothalamus. The brain traumatization does not influence the rate of disjunction of separated glial cells. Angles between axes of separated cells are different in the brain regions under study. In cortex and white matter, separated cells with axial angles equal to 180 degrees predominate whereas in thalamus, hypothalamus and subependymal zone many separated cells have axial angles below 180 degrees (120-160 degrees). The possible relationship between the form of the brain regions under study and the value of axial angles of separated cells is discussed.

Animals↗

PubMed2005

Phylogeography and demography of sympatric sister surfperch species, Embiotoca jacksoni and E. lateralis along the California coast: historical versus ecological factors.

With 18 closely related endemic species that radiated in a diversity of ecological niches, the California surfperches (Embiotocidae) species flock is a good candidate for the study of sympatric speciation. Resource partitioning has been suggested as an important driving force in the radiation of the surfperch family. Within the family, two congeneric sister species, Embiotoca jacksoni and E. lateralis, are known to compete strongly for a preferred single food resource and may be used as a model of ecological interactions for the family. Along the California coast, the distribution of the two species differs. Embiotoca jacksoni has a continuous range, whereas E. lateralis shows a disjunction with a distribution gap in the Southern California Bight. Two hypotheses may explain this disjunct distribution. Ecological competition may have displaced E. lateralis in favor of E. jacksoni. Alternatively, a common vicariant event may have separated the species into northern and southern populations, followed by secondary contact in E. jacksoni but not in E. lateralis. The two hypotheses predict different phylogeographic and demographic signatures. Using a combined phylogeographic and coalescent approach based on mitochondrial control region data, we show that vicariance can only account for a portion of the observed divergences. Our results are compatible with a significant role played by ecological competition in the southern range of the species.

Animals↗

PubMedDate not supplied

[Molecular cytogenetic study of Robertsonian translocation 13;14 and Down syndrome in a 3-year-old infant].

We describe here a rare case of Robertsonian translocation 13;14 of maternal origin combined with regular trisomy 21 (46,XX,der(13;14)(q10;q10)mat,+21) with Down syndrome phenotype. Molecular cytogenetic studies allowed us to determine the maternal origin of additional chromosome 21 and the non-disjunction of chromosome 21 to occur in meiosis I. On the basis of data obtained we discuss the possible involvement of structural alterations of chromosomes 13 and 14 in the chromosome 21 non-disjunction.

Child, Preschool↗

PubMedDate not supplied

Advancing acupuncture research.

Since the early 1970s, acupuncture has been the subject of multiple animal experiments and randomized clinical trials. Our understanding of acupuncture from both the clinical and mechanistic perspectives has, as a result, grown tremendously. Yet the final word on acupuncture as a therapy remains mixed, largely due to the contradictory nature of the evidence. With some exception, what clinical conditions would benefit and how acupuncture physiologically operates remains unclear. The impediment to progress is found in three disjunctions in acupuncture research: (1) the biomedical need to standardize treatments creates uncertainty about whether we are studying acupuncture appropriately; (2) the variability in acupuncture styles creates ambiguity about whether we are studying the right style; and (3) the discrepancy between animal and human studies creates questions about whether we truly understand the underlying mechanism responsible for acupuncture's therapeutic effect. We propose that these disjunctions are best addressed with the use of "manualized" protocols in clinical trials that are linked with mechanistic studies. Through this approach, we can create a healthy dialogue between the medical and acupuncture communities and recognize the unique physiologic properties that may be found in each acupuncture style. To illustrate how this proposal may fundamentally change acupuncture research, we present diabetic neuropathy as a particularly interesting model because of its complex heterogeneous pathophysiology.

Acupuncture Analgesia↗

PubMed2005

Investigating the evolutionary history of the Pacific Northwest mesic forest ecosystem: hypothesis testing within a comparative phylogeographic framework.

We examine the evolution of mesic forest ecosystems in the Pacific Northwest of North America using a statistical phylogeography approach in four animal and two plant lineages. Three a priori hypotheses, which explain the disjunction in the mesic forest ecosystem with either recent dispersal or ancient vicariance, are tested with phylogenetic and coalescent methods. We find strong support in three amphibian lineages (Ascaphus spp., and Dicampton spp., and Plethodon vandykei and P. idahoensis) for deep divergence between coastal and inland populations, as predicted by the ancient vicariance hypothesis. Unlike the amphibians, the disjunction in other Pacific Northwest lineages is likely due to recent dispersal along a northern route. Topological and population divergence tests support the northern dispersal hypothesis in the water vole (Microtus richardsoni) and northern dispersal has some support in both the dusky willow (Salix melanopsis) and whitebark pine (Pinus albicaulis). These analyses demonstrate that genetic data sampled from across an ecosystem can provide insight into the evolution of ecological communities and suggest that the advantages of a statistical phylogeographic approach are most pronounced in comparisons across multiple taxa in a particular ecosystem. Genetic patterns in organisms as diverse as willows and salamanders can be used to test general regional hypotheses, providing a consistent metric for comparison among members of an ecosystem with disparate life-history traits.

Amphibians↗

PubMed1992

Meiotic and sperm chromosome analysis in a male carrier of an inverted insertion (3;10)(q13.2;p14p13).

A phenotypically normal male who fathered a son with the karyotype 46,XY,del(10)(p13) was found to be a balanced carrier of an inverted insertion (3;10) (q13.2;p14p13). Karyotyping five later pregnancies showed four to be unbalanced with respect to the insertion, one of which was also trisomic for chromosome 18. The latest pregnancy was balanced with respect to insertion but had the additional complexity of 47,XXY. In the light of six out of six chromosomally abnormal pregnancies, two of which potentially exhibit an interchromosomal effect, it was decided to investigate the gametic output of the father. Testicular biopsy and semen samples were obtained permitting both meiotic and sperm chromosome analysis. Information was thus obtained at three levels of gamete production, that is, prophase I pairing, chiasma frequency distribution at metaphase I, and sperm karyotypes. Electron microscope studies of synaptonemal complexes showed the rearranged chromosomes to pair fully in meiotic prophase I with no indication of the presence of an insertion. This non-homologous pairing of the inserted region was accompanied by an abnormal frequency distribution of pachytene substages. There was also a reduction in chiasma frequency throughout the genome. However, this did not lead to detectable autosomal univalence or abnormally high X/Y univalence. Thus, the trisomy 18 and XXY pregnancies are unlikely to reflect increased non-disjunctional rates either before or during the first meiotic division. Sperm karyotyping showed that the proportion of chromosomally balanced:unbalanced gametes did not differ from the theoretically expected 1:1. There was no evidence of any increase of unrelated abnormalities in the sperm, further indicating that the overall rate of meiotic non-disjunction was not increased above normal.

Adult↗

PubMed2005

Double aneuploidy in three Egyptian patients: Down-Turner and Down-Klinefelter syndromes.

The co-occurrence of two numerical chromosomal abnormalities in same individual (double aneuploidy) is relatively rare and its clinical presentations are variable depending on the predominating aneuploidy or a combination effect of both. Furthermore, double aneuploidy involving both autosomal and sex chromosomes is seldom described. In this study, we present three patients with double aneuploidy involving chromosome 21 and sex chromosomes. They all had the classical non disjunction trisomy 21; that was associated with monosomy X in two of them and double X in the other. Clinically, they had most of the phenotypic features of Down syndrome as well as variable features characteristic of Turner or Klinefelter syndrome. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis were carried out for all patients and their parents. The first patient was a male, mosaic with 2 cell lines (45,X/47,XY,+21) by regular banding techniques and had an affected sib with Down syndrome (47,XY,+21). The second was a female, mosaic (46,X,+21/47,XX,+21) where monosomy X was detected only by FISH in 15 percentages of cells, nevertheless, stigmata of Turner syndrome was more obvious in this patient. The third patient had non mosaic double trisomy; Down-Klinefelter (48,XXY,+21) presented with Down syndrome phenotype. Parental karyotypes and FISH studies for these patients were normal with no evidence of mosaicism. In this report, we review the variable clinical presentations among the few reported cases with the same aneuploidy in relation to ours. Also, the proposed mechanisms of double aneuploidy and the occurrence of non-disjunction in more than one family member are discussed. This study emphasizes the importance of molecular cytogenetics studies for more than one tissue in cases with atypical features of characteristic chromosomal aberration syndromes. To our knowledge, this is the first report of double aneuploidy, Down-Turner and Down-Klinefelter syndromes in Egyptian patients.

Aneuploidy↗

PubMed2005

Nonrandom larval dispersal can steepen marine clines.

Sharp and stable clinal variation is enigmatic when found in species with high gene flow. Classical population genetic models treat gene flow as a random homogenizing force countering local adaptation across habitat discontinuities. Under this view, dispersal over large spatial scales will lower the effectiveness of adaptation by natural selection at finer spatial scales. Thus, random gene flow will create a shallow phenotypic cline across an ecotone in response to a steep selection gradient. In sedentary marine species that disperse primarily as larvae, nonrandom dispersal patterns are expected due to coastal hydrodynamics. Surprisingly sharp phenotypic and genotypic clines have been documented in marine species with high gene flow. We are interested in the extent to which nonrandom dispersal could accentuate such clines. We model a linear species range in which populations have stable and uniform densities along a selection gradient; in contrast to random dispersal, convergent advection of larvae can amplify phenotypic differentiation if coupled with a semipermeable dispersal barrier in the convergence zone. The migration load caused by directional dispersal pushes the phenotypic mean away from the local trait optimum in downstream populations, that is, near the convergence zone. A dispersal barrier is possible as a result of colliding currents if the water and larvae are mostly displaced offshore, away from suitable settlement habitat. Disjunctions in a quantitative trait were enlarged in the convergence zone by faster current flows or a more complete dispersal barrier. With advection of larvae per generation one-third as far as the average dispersal distance by diffusion, convergence on a dispersal barrier with 40% permeability generated a trait disjunction across the convergence zone of two phenotypic standard deviations. Without directional dispersal, similar clines also developed across a habitat gap, where population density was low, or across dispersal barriers with less than 1% permeability. These findings suggest that the types of hydrographic phenomena often associated with marine transition zones can strongly affect the balance between gene flow and selection and generate surprisingly steep clines given the large-scale gene flow expected from larvae.

Animal Migration↗

PubMed1990

Loss of heterozygosity in Wilms' tumour involves two distinct regions of chromosome 11.

Pairs of tumour and normal DNA samples from 38 Wilms' tumour patients have been investigated for loss of heterozygosity using 12 probes from chromosome 11. Allele loss was detected in only 11 cases (31%). Densitometric analysis showed that allele loss was not due to non-disjunction or hemizygous deletion, but rather to mitotic recombination or non-disjunction plus reduplication. Although the development of homozygosity sometimes involved the whole of the short arm of chromosome 11, in a few tumours allele loss was restricted to band 11p15 or 11p13 and distal sequences. This suggests mutations in two distinct regions play an important role in Wilms' tumorigenesis. There was no apparent correlation between loss of heterozygosity and tumour stage, age of presentation, or prior exposure to chemotherapy.

Alleles↗

PubMed1990

[Traumatic acromio-clavicular pathology].

Based on clinical and radiological findings, four types of acromioclavicular disjunction are described. Stage I and II require nothing more than orthopaedic appliances, whereas surgery is mandatory in stage IV. Treatment of stage III disjunctions varies from on school of orthopaedists to the other. Fractures of the lateral third of the clavicle may lead to diagnostic errors, and tomography is justified at the slightest doubt concerning the integrity of the acromial end of that bone.

Acromioclavicular Joint↗

PubMed1990

[Morphological observation of the mitral annulus fibrosus in patients with mitral valve prolapse].

Sixteen cases of mitral valve prolapse (MVP) with mitral regurgitation (MR) in the aged (mainly in their eighth and ninth decades) with both clinical and pathological evidences were investigated. One hundred autopsy cases served as the control. The longitudinally-sectioned mitral annulus fibrosus was pathologically studied in all with special reference to the atrium-valve disjunction reported by Hutchins. Morphologically, the mitral annulus fibrosus was classified either as type A (the mitral valve attaches to the left ventricle), type B (the mitral valve attaches to the left atrium: Hutchins' disjunction), type C (the atrialis continues to the left atrium and the fibrosa to the left ventricle), or type D (mitral annulus calcification). Type B was observed in only 31% of the MVP cases, whereas it was seen in 43% of the control cases. It was concluded that Hutchins' observation could not be regarded as the characteristic pathological finding of MVP.

Aged↗

PubMed1989

Meiotic segregation of normal and deletion chromosomes in Saccharomyces cerevisiae.

We explored the behavior of meiotic chromosomes in Saccharomyces cerevisiae by examining the effects of chromosomal rearrangements on recombination and disjunction. Chromosome III derivatives in which the entire left arm or the entire right arm was deleted (telocentric) segregated with fidelity from a normal chromosome III. Recombination between either of these two deletion chromosomes and the intact chromosome also appeared normal. In a strain containing a right arm telocentric, a left arm telocentric and one normal chromosome both telocentrics disjoined from the normal chromosome. Homology on one arm was sufficient for proper recombination and segregation of these chromosomes. In strains containing two normal chromosomes and one telocentric chromosome the two normal chromosomes preferentially disjoined. In a few cases however, the two normal chromosomes cosegregated. Recombination between the two normal chromosomes or between one normal chromosome and the deletion chromosome increased the probability that they would disjoin, although cosegregation of recombinants was observed. A chromosome III derivative which contained a large centromeric deletion and an insertion of the centromere from chromosome V into a nonhomologous position segregated with fidelity from a normal chromosome III. These studies demonstrate that it is not pairing of the centromeres, but pairing and recombination along the arms of the homologs that directs meiotic chromosome disjunction.

Chromosome Deletion↗

PubMed1986

Recessive lethal t haplotypes increase the frequency of the partial trisomy of chromosome 17 (including the T-t complex) among offspring of T(16;17)43H female mice.

The male-sterile reciprocal autosomal translocation T(16;17)43H displays a high frequency of adjacent-2 disjunction in meiosis of translocation heterozygotes. One haploid product of this abnormal chromosome segregation leads to viable partial trisomy of chromosome 17 after fertilization. The frequency of trisomics increases in the progeny of T43H/+ females when the wild-type allelic form of T-t complex is substituted for t12, tw32 or t6 recessive lethal haplotypes. Indirect evidence supports the idea that the suppression of crossing-over by t haplotypes is linked with the increase in adjacent-2 disjunction and subsequent Ts43H trisomy. The possible use of Ts43H trisomy for genetic dissection of the T-t complex is briefly discussed.

Animals↗