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Evolution of the 28S ribosomal RNA gene in anurans: regions of variability and their phylogenetic implications 总被引:1,自引:0,他引:1
Fifteen restriction sites were mapped to the 28S ribosomal RNA gene of
individuals representing 54 species of frogs, two species of salamanders, a
caecilian, and a lungfish. Eight of these sites were present in all species
examined, and two were found in all but one species. Alignment of these
conserved restriction sites revealed, among anuran 28S rRNA genes, five
regions of major length variation that correspond to four of 12 previously
identified divergent domains of this gene. One of the divergent domains
(DD8) consists of two regions of length variation separated by a short
segment that is conserved at least throughout tetrapods. Most of the
insertions, deletions, and restriction-site variations identified in the
28S gene will require sequence-level analysis for a detailed reconstruction
of their history. However, an insertion in DD9 that is coextensive with
frogs in the suborder Neobatrachia, a BstEII site that is limited to
representatives of two leptodactylid subfamilies, and a deletion in DD10
that is found only in three ranoid genera are probably synapomorphies.
相似文献
4.
Karyometry and histometry of renal-cell carcinoma 总被引:1,自引:0,他引:1
M Bibbo H Galera-Davidson H E Dytch J Gonzalez de Chaves J Lopez-Garrido P H Bartels G L Wied 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1987,9(2):182-187
In an attempt to more objectively predict the outcome of renal cancers, karyometric and histometric studies were performed using an interactive computer-based system for the quantitative analysis of tissue sections. Analysis showed a significant relationship between patient survival and metastases and the histometric parameters of nuclear elongation, nuclear crowding and mitotic density, as well as tumor grade. Patients who died tended to have a high mitotic density, elongated and crowded nuclei and high-grade tumors. Ploidy showed no significant correlation with prognosis while nuclear elongation and crowding did. Differences in histologic grade were significantly associated with several histometric variables, including nuclear area, shape, crowding, elongation and mitotic density. 相似文献
5.
In rat liver parenchyma, expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene was studied by Northern blot analysis with a biotinylated cRNA probe and the zonal localization of PEPCK mRNA was demonstrated by in situ hybridization with a radiolabelled cRNA probe. During the feeding period at night, overall PEPCK mRNA levels were low and PEPCK mRNA was detected only in small areas of the periportal zone. At the beginning of the light period (7 am) the overall PEPCK mRNA level began increasing and the periportal areas containing PEPCK mRNA broadened. The maximum of the total abundance and of the area with high levels of PEPCK mRNA was reached at noon. Fasting for 24-72 h did not cause further significant alterations in the level or localization of PEPCK mRNA. The present data are in line with previous findings of the predominant localization of PEPCK activity and enzyme protein in periportal hepatocytes. They suggest that the heterogeneous expression of the PEPCK gene in rat liver is regulated at the pretranslational level. 相似文献
6.
H Galera-Davidson P H Bartels A Fernandez-Rodriguez H E Dytch E Lerma-Puertas M Bibbo 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1990,12(1):35-41
Karyometric measurements were performed on fine needle aspirates of clearly identifiable tumor areas and adjacent normal-appearing areas in the surgical specimens from ten patients with invasive follicular carcinoma of the thyroid. Similar measurements were performed on aspirates from nine patients free of thyroid disease (controls). A total of 95 karyometric features were evaluated for each nucleus. Analysis of variance of optical density values indicated (1) a similarity between tumor and normal-appearing nuclei from carcinoma cases, (2) a significant difference between those nuclei and control nuclei and (3) that most of the differences were due to the differences of tissue origin. Stepwise linear discriminant analysis selected ten features that produced a statistically highly significant separation of tumor nuclei from control nuclei. A similar analysis selected six features that produced a statistically highly significant discrimination of normal-appearing nuclei from control nuclei; the validity of those karyometric features as markers of malignancy in normal-appearing nuclei from tissues adjacent to invasive follicular carcinomas of the thyroid was demonstrated by analysis in further training and control sets of nuclei. This analysis in thyroid aspirates identified more marker features than did a previous similar analysis using tissue sections. 相似文献
7.
The isolated liver from 24 h fasted rats was perfused in a non-recirculating manner in the ortho- and retrograde direction with erythrocyte-containing (20% v/v) media to provide adequate oxygenation of the liver. Glucose and/or gluconeogenic precursors were added as substrates. Glycogen formation was determined biochemically and demonstrated histochemically. With glucose as the sole exogenous substrate glycogen was deposited in the perivenous area, with gluconeogenic precursors it was formed in the periportal zone during ortho- and retrograde flow. When glucose and gluconeogenic compounds were offered together, glycogen was deposited in both zones. The results corroborate the model of metabolic zonation predicting that periportal glycogen is synthesized indirectly from gluconeogenic precursors while perivenous glycogen is formed directly from glucose. 相似文献
8.
S W Jordan J M Brayer P H Bartels R E Anderson 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1988,10(1):37-46
Obtaining histologic images for computer-based morphometric analysis is associated with a number of standardization problems, which must be solved if reproducible data collection is expected. These problems include tissue processing, sectioning and staining, standardizing and calibrating the video camera and determining the appropriate sampling rate (pixels/micron). Suggested solutions for these problems are presented for a specific image analysis system, but are applicable to other systems with similar capabilities. Biologic variability is not eliminated by computer-assisted analysis, so it is important to minimize data-collection artifacts by parallel processing of experimental and control material, as in other investigative work. 相似文献
9.
P H Bartels D Thompson J E Weber 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1992,14(1):1-13
Expert systems deal with data that are categorical and conceptual, that represent elements of fuzzy sets and that often, by themselves, do not allow an unequivocal decision. The management of uncertainty in expert systems thus becomes a crucial issue. It involves defining measures of uncertainty and procedures for combining accumulating evidence in a manner that properly considers the dependence structure of diagnostic clues. Probability theory offers valuable procedures for uncertainty assessment; however, their practical application in the domain of quantitative histopathology and histopathologic diagnosis can be problematic. 相似文献
10.
Correlation between automated DNA ploidy measurements of Hürthle-cell tumors and their histopathologic and clinical features 总被引:1,自引:0,他引:1
H Galera-Davidson M Bibbo P H Bartels H E Dytch J H Puls G L Wied 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1986,8(2):158-167
The treatment of Hürthle-cell tumors of the thyroid is controversial because of their rarity and the inconsistent histopathologic criteria for their diagnosis. In order to obtain more objective criteria for the management of Hürthle-cell tumors, the nuclear DNA content of cells from 20 cases was measured with the MicroTICAS system and the correlation between the DNA distribution patterns and the clinical and histopathologic findings was evaluated. Three main DNA patterns were found: euploid, polyploid and aneuploid. The euploid or polyploid Hürthle-cell tumors came from patients who did not develop distant metastases or recurrence whereas the aneuploid variants came from patients who died of their disease and/or developed distant metastases and recurrence. Various correlation analyses were performed between DNA ploidy and age, sex, size of tumor, growth pattern, pleomorphism, invasion and metastases. Our data suggests that an aneuploid DNA pattern or one with a large percentage of aneuploid nuclei with DNA content exceeding 5N may predict eventual metastases or recurrence from Hürthle-cell tumor. 相似文献