			Home About us Contact

Vertebral Number (vertebral + number)

Distribution by Scientific Domains

Life Sciences	72%

Selected Abstracts

Jordan's and other ecogeographical rules, and the vertebral number in fishes

JOURNAL OF BIOGEOGRAPHY, Issue 3 2008
R. M. McDowall
Abstract Aim, To explore variation in the number of vertebrae in fishes in the context of Jordan's rule and other ecogeographical rules. Location, Global. Methods, The study is based on literature review. Results, The number of vertebrae varies very widely across the diversity of fishes. Jordan's rule states that vertebral number increases with latitude, and this is widely attributed to ambient temperatures during ontogeny of individual fishes. However, the number of vertebrae may depend on both the ontogenetic environment and inheritance. Diverse other aspects of fish development and ecology are suggested as influencing vertebral number, including fish size, phyletic position, body shape and swimming mode. Main conclusions, The number of different factors that influence the number of vertebrae in fishes makes for highly complex patterns of variation, and means that unravelling causes is difficult. The question needs to be addressed at the population/species/species group scale; moreover, the lack of discrimination between environmental and inherited causes of variation adds to the complexity. [source]

Genetic evidence for the introgression of Western NR6A1 haplotype into Chinese Licha breed associated with increased vertebral number

ANIMAL GENETICS, Issue 2 2009
G. Yang
Summary There is evidence that NR6A1 is a strong candidate for being a causal gene underlying vertebral number in pigs. The Licha Black is one of the leanest Chinese indigenous pig breeds, having an average vertebral number of 21.5. The introgression of Western germplasm into Licha Black, resulting in increased vertebral number, has been assumed but is not confirmed. This study detected allele frequencies of the NR6A1 causative mutation (c.575T>C) in 519 pigs from three Western and seven Chinese breeds including Licha Black, and evaluated the genetic variation in a 650-kb region containing NR6A1 in the 10 breeds. Allele T for increased vertebral number was fixed in Western breeds. In contrast, this allele was very rare in most of the Chinese native breeds. Notably, the T allele was present in the Licha Black at a rather higher frequency (0.585) and in the Laiwu at lower frequency (0.250). As expected, selection pressure has wiped out the genetic variability in the 650 kb region in Western breeds. Conversely, Chinese indigenous breeds showed a high degree of genetic variability in this region. However, the Licha Black displayed dramatically reduced heterozygosity at the loci proximal to the causative mutation. Moreover, a high proportion (45.9%) of Licha Black pigs and a small number (21%) of Laiwu pigs had the Western NR6A1 haplotype, and the two breeds showed closer relationships with Western commercial breeds than other Chinese breeds in the phylogenic tree. When the results are taken together, this study supports the assumption that the Western NR6A1 haplotypes were introduced into Licha Black and possibly Laiwu and are associated with increased vertebral number. [source]

Latitudinal variation in axial patterning of the medaka (Actinopterygii: Adrianichthyidae): Jordan's rule is substantiated by genetic variation in abdominal vertebral number

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
KAZUNORI YAMAHIRA
Because the body axes of fish consist of two anatomically distinct vertebrae, abdominal and caudal, one type may be more variable in number than the other and thus contribute more to morphological diversification. Jordan's rule, a geographical tendency for fish from higher latitudes to have more vertebrae, has not been examined in terms of numbers of abdominal and/or caudal vertebrae, despite its prevalence. Vertebral observations of wild populations of the medaka (Oryzias latipes) revealed that the latitudinal increase in vertebral number is caused by an increase in abdominal vertebrae; caudal vertebrae did not vary systematically across latitudes. Laboratory experiments revealed that this latitudinal cline in abdominal vertebral number persists in a range of common environments, demonstrating a genetic basis. Phenotypic plasticity was also evident: lower developmental temperatures resulted in more abdominal vertebrae. This indicates that greater numbers of abdominal vertebrae in higher latitude individuals in the wild may be caused not only by genetic factors but by lower habitat temperatures, although the contribution of the former to Jordan's rule is assessed to be much greater. The genetic basis of the latitudinal variation in abdominal vertebral number suggests that selection on functions associated with abdominal regions is the probable explanation for Jordan's rule in this fish. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 856,866. [source]

Heritability and genetic correlation of abdominal versus caudal vertebral number in the medaka (Actinopterygii: Adrianichthyidae): genetic constraints on evolution of axial patterning?

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
KAZUNORI YAMAHIRA
Variation in the number of abdominal vs. caudal vertebrae is an important source of morphological diversification of fish. It is not clear, however, whether abdominal and caudal regions evolve independently. Regressions of offspring on parents demonstrated substantial additive genetic variation within populations, i.e. heritability, in both abdominal and caudal vertebral numbers of the medaka (Oryzias latipes). However, the heritability of caudal vertebrae tended to be smaller than that of abdominal vertebrae in some estimations, suggesting that abdominal and caudal regions are controlled by separate developmental modules. Furthermore, genetic correlation between abdominal and caudal vertebral numbers, estimated using full-sib family means, was negative but weak, supporting independent evolution. In addition, substantial genetic differentiation among populations was demonstrated in abdominal vertebral numbers, but not in caudal numbers. These results support our view that Jordan's rule, a geographical tendency for fish from higher latitudes to have more vertebrae, in this fish reflects local adaptations of abdominal vertebral numbers. In contrast, the low heritability of caudal vertebrae may reflect the intrinsic invariability of genes associated with a change in caudal vertebral numbers. This genetic constraint may have restricted morphological diversification of not only the medaka, but also the Order Beloniformes as a whole. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 867,874. [source]

Treatment of lumbar and lumbosacral spinal tuberculosis with minimally invasive surgery

ORTHOPAEDIC SURGERY, Issue 1 2010
Xi-feng Zhang MD
Objective:, To evaluate the outcome of computed tomography (CT)-guided percutaneous puncture and local chemotherapy for tuberculosis (TB) of the lumbar or lumbosacral spine. Methods:, From January 2002 to August 2006, 49 patients with lumbar or lumbosacral spinal TB in whom conservative treatment had failed were treated by minimally invasive surgery. There were 21 female and 28 male patients. The mean age of the patients was 47 ± 18 years (range from 12 to 78 years). There were 40 cases with lumbar TB, and 9 with lumbosacral TB. From L1 to S1, the involved vertebral numbers were 8, 26, 19, 19, 21 and 10, respectively. In 3 patients the spinal TB involved a single vertebra, in 39 patients two, in 6 patients three and in only one case four vertebrae. According to the Frankel scale, three patients had grade E incomplete paralysis preoperatively. The outcome, after treatment by CT-guided percutaneous puncture and local chemotherapy, was retrospectively analyzed according to the preoperative and postoperative kyphotic angles and the Oswestry disability index (ODI). Results:, Forty-nine patients were followed up for from one year to 5 years and 8 months (average 35 months). All cases recovered, and there was no recurrence. Preoperatively, the kyphotic angle was 16.47°± 8.74°, and it had decreased to 13.35°± 8.02° by the final follow-up (t= 5.79, P < 0.001). The average ODI score had improved from 70.12 ± 22.24 to 12.72 ± 8.62 (t= 21.42, P < 0.001). Conclusion:, The majority of cases of lumbar and lumbosacral spinal TB can achieve satisfactory results with minimally invasive surgery. Its clinical application is therefore strongly recommended. [source]

Heritability and genetic correlation of abdominal versus caudal vertebral number in the medaka (Actinopterygii: Adrianichthyidae): genetic constraints on evolution of axial patterning?