Evolution of the 28S ribosomal RNA gene in anurans: regions of variability and their phylogenetic implications

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.      

Common expression of a tumor necrosis factor resistance mechanism among gynecological malignancies

Summary The efficacy of tumor necrosis factor (TNF) as an anticancer agent is limited. This limitation might be related to the expression of a protein-synthesis-dependent resistance mechanism that prevents the lysis of tumor cells by TNF. To test this possibility eight randomly selected human cell lines, three derived from ovarian carcinomas and five derived from cervical carcinomas, were tested for their in vitro sensitivity to TNF-mediated lysis. The results of this analysis showed that all eight cell lines are normally resistant to lysis by TNF. However, in the presence of inhibitors of protein synthesis, seven of them showed a significant increase in TNF-mediated lysis. Measurement of protein synthesis showed that there is a linear correlation between the level of inhibition of protein synthesis and the level of TNF-mediated lysis. The fact that seven of eight randomly selected cell lines are resistant to TNF because they express a protein-synthesis-dependent resistance mechanism suggests that this mechanism of resistance may be common among gynecological cancers. The results also suggest that a therapy involving TNF and inhibitors of protein synthesis might be useful for the treatment of gynecological malignancies.     

Variation in the ribosomal internal transcribed spacers and 5.8S rDNA among five species of Acropora (Cnidaria; Scleractinia): patterns of variation consistent with reticulate evolution

The ITS sequences of Acropora spp. are the shortest so far identified in any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80 bases, and ITS2 was 100-112 bases. The ITS sequences were also highly variable, but base composition and secondary structure prediction indicate that divergent sequence variants are unlikely to be pseudogenes. The pattern of variation was unusual in several other respects: (1) two distinct ITS2 types were detected in both A. hyacinthus and A. cytherea, species known to hybridize in vitro with high success rates, and a putative intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was found to contain highly (29%) diverged ITS1 variants; and (3) A. longicyathus contained two distinct 5.8S rDNA types. These data are consistent with a reticulate evolutionary history for the genus Acropora.      

Activin induces x-zone apoptosis that inhibits luteinizing hormone-dependent adrenocortical tumor formation in inhibin-deficient mice

Inhibin and activin are members of the transforming growth factor beta (TGF-beta) family of ligands produced and secreted primarily by the gonads and adrenals. Inhibin-null (INH(-/-)) mice develop gonadal tumors and-when gonadectomized-adrenocortical carcinoma. The mechanisms leading to adrenal tumorigenesis have been proposed to involve the lack of a gonadal factor and/or a compensatory increase in gonadotropins. In order to achieve elevation of gonadotropins without the concomitant loss of a gonadal hormone, we crossed INH(-/-) mice with a transgenic mouse strain that has chronically elevated luteinizing hormone (LH) levels (LH-CTP). Compound INH(-/-)-LH-CTP mice die within 6 weeks of age from severe cancer cachexia induced by large, activin-secreting ovarian tumors. Unexpectedly, INH(-/-)-LH-CTP mice not only fail to develop adrenal tumors but have smaller adrenals, with a regressed x zone, indicating that elevated LH levels are not sufficient to induce adrenal tumor formation. However, following gonadectomy, INH(-/-)-LH-CTP mice develop large, sex steroid-producing adrenal tumors that arise from the x zone, indicating a growth-promoting effect of high levels of LH on the adrenal cortex in the absence of ovarian tumors. In addition, in vivo and in vitro data indicate that activin induces apoptosis specifically in the adrenal x zone. The restricted expression of activin receptor subunits and Smad2 in cells of the adrenal x zone, together with the elevated activin levels in INH(-/-)-LH-CTP mice, supports the conclusion that activin inhibits adrenal tumor growth by inducing x-zone regression.     

Transvaginal fine needle aspiration biopsy.

OBJECTIVE: To assess the role of transvaginal fine needle aspiration biopsy (FNAB) in the evaluation of palpable gynecologic masses. STUDY DESIGN: Transvaginal FNABs from 1994 to 1999 were identified from the files of Barnes-Jewish Hospital. Histologic correlation was obtained using the Pathology Department's computer database. Two pathologists reviewed the pathologic samples. Pertinent clinical information was obtained by reviewing the medical records. RESULTS: Twenty-two transvaginal FNABs from 22 patients were studied. The patients' mean age was 59 years (range, 29-84). Most patients (77%) had a previous history of a gynecologic malignancy, and 73% had a previous total abdominal hysterectomy and bilateral salpingo-oophorectomy. The size of the lesion sampled was provided in 15 cases and ranged from <1 to 5.4 cm in diameter. The location of the mass was reported as follows: vaginal (10 cases), vaginal cuff (5), rectovaginal septum (2), cul-de-sac (1), fornix (1), vaginal apex (1), right side of pelvis (1), and not specified (1). The cytologic diagnoses were: negative for malignancy (10 cases), positive for malignancy (9) and unsatisfactory (3). Most cases (77%) had histologic correlation or clinical follow-up. There was one false negative and no false positive cytologic diagnosis. CONCLUSION: Cytologic interpretation of transvaginal FNAB is an effective toolfor the evaluation of palpable pelvic and vaginal masses. Its specificity and sensitivity are 100% and 88%, respectively.     

Evidence for "twisted plane" undulations in golden hamster sperm tails

Motile spermatozoa from the golden hamster have been arrested by rapid freezing and then fixed with glutaraldehyde at low temperature after substitution with ethylene glycol. As far as can be judged, the flagellar waveforms thus stabilized are similar to those seen in living sperm; in contrast, fixation in glutaraldehyde, without prior freezing, induces agonal changes in flagellar conformation. The characteristics waveform after freeze substitution contains three bends. Approx. half of these flagella are entirely planar. The rest are three dimensional, with the third bend displaced in a regular way from the plane containing the proximal two bends. From the geometry of these flagella, it is concluded that the plane of action of a given bending cycle undergoes a clockwise twist (from a forward viewpoint) as the cycle is succeeded by new bending cycles. This "twisted plane" undulation is quite different from helical movement. The twisting seems to occur abruptly, between cycles, as if each bending cycle has a preferred plane of action. The mechanism underlying the twisting is uncertain. However, on the basis of the angular displacements between the preferred planes, and the findings from electron microscopy, the following idea is presented as a working hypothesis: that, if the most proximal plane of bending is topographically determined by peripheral doublet 1, then successive distal planes of action are influenced predominantly by doublets 2, 3, etc., in clockwise sequence. The merits and weaknesses of this hypothesis are discussed.     

Impact of human activities on the reproduction of Hooded Vultures Necrosyrtes monachus in Burkina Faso

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.     

Diversity and specificity of Rhizobium leguminosarum biovar viciae on wild and cultivated legumes

The symbiotic partnerships between legumes and their root-nodule bacteria (rhizobia) vary widely in their degree of specificity, but the underlying reasons are not understood. To assess the potential for host-range evolution, we have investigated microheterogeneity among the shared symbionts of a group of related legume species. Host specificity and genetic diversity were characterized for a soil population of Rhizobium leguminosarum biovar viciae (Rlv) sampled using six wild Vicia and Lathyrus species and the crop plants pea (Pisum sativum) and broad bean (Vicia faba). Genetic variation among 625 isolates was assessed by restriction fragment length polymorphism (RFLP) of loci on the chromosome (ribosomal gene spacer) and symbiosis plasmid (nodD region). Broad bean strongly favoured a particular symbiotic genotype that formed a distinct phylogenetic subgroup of Rlv nodulation genotypes but was associated with a range of chromosomal backgrounds. Host range tests of 80 isolates demonstrated that only 34% of isolates were able to nodulate V. faba. By contrast, 89% were able to nodulate all the local wild hosts tested, so high genetic diversity of the rhizobial population cannot be ascribed directly to the diversity of host species at the site. Overall the picture is of a population of symbionts that is diversified by plasmid transfer and shared fairly indiscriminately by local wild legume hosts. The crop species are less promiscuous in their interaction with symbionts than the wild legumes.