Apoptosis is physiologically restricted to a specialized cytoplasmic compartment in rat spermatids

Cytoplasmic caudal tags of maturing spermatids condense and are detached from the spermatidal cells just before the spermatids are released as spermatozoa. The detached cytoplasmic masses are termed "residual bodies." Features of residual bodies seem to be compatible with those of apoptosis and, just as occurs with apoptotic bodies, residual bodies are phagocytosed by Sertoli cells. Since in vitro studies have demonstrated that nucleus and cytoplasm apoptosis events can be independent phenomena, we reasoned that apoptosis pathways might be restricted to the caudal tag of the maturing spermatids in order to originate residual bodies. Consistent with this idea, here we showed that annexin V specifically bound the membranes of isolated residual bodies and that expression levels of caspase-1, c-jun, p53, and p21 were specifically increased in these cytoplasmic compartments. Electron microscopy of cytoplasmic lobes and residual bodies confirmed that their ultrastructural features were those of apoptosis. These data indicate that the mechanism responsible for the formation of residual bodies is similar to that for apoptotic bodies; and the study presents evidence, for the first time, that apoptotic signaling molecules can be restricted to a cytoplasmic compartment and proceed in the presence of a healthy nucleus.     

Cloning and characterization of a regulatory gene of the SARP family and its flanking region from Streptomyces ambofaciens

In a search for activators of secondary metabolism we isolated a 12.6-kb DNA fragment from a genomic library of Streptomyces ambofaciens NRRL 2240 (the spiramycin producer ). Sequencing of 6 kb of the cloned fragment revealed a cluster of four ORFs (ORF1–4) whose deduced products showed similarities to those of other genes involved in polyketide biosynthesis, including a pathway-specific regulatory gene of the SARP family. The results of insertional inactivation of some of the cloned genes clearly indicate that the isolated cluster does not code for spiramycin production, suggesting that some other polyketide compound might well be produced by this strain. Received: 14 May 1999 / Accepted: 28 July 1999     

Biology of Triatoma pallidipennis stal 1945 (Hemiptera: Reduviidae:Triatominae) under laboratory conditions

Aspects related to hatching, life time, mortality, feeding behaviour and fecundity for each stage of Triatoma pallidipennis life-cycle were evaluated. The hatching rate observed for 200 eggs was 60% and the average time of hatching was 18 days. Eighty nymphs (N) (40%) completed the cycle and the average time from NI to adult was 168. 7+/-11.7days. The average span in days for each stage was 18.0 for NI, 18.5 for NII, 30.0 for NIII, 35.7 for NIV and 50.1 for NV. The number of bloodmeals at each nymphal stage varied from 1 to 5. The mortality rate was 9.17 for NI, 5.5 for NII, 6.8 for NIII 4.17 for NIV and 13.04 for NV nymphs. The average number of eggs laid per female in a 9-month period was 498.6. The survival rates of adults were 357+/-217.9 and 262.53+/-167.7 for males and females respectively.     

Correlation of rhodamine 123 efflux by neoplastic plasma cells with clinical and biological characteristics of multiple myeloma

Although a variable proportion of multiple myeloma patients can achieve response with conventional chemotherapy, residual tumor cells, which are refractory, finally reemerge leading to disease progression. The expression of the multidrug resistance protein (MDR1) has been one of the most extensively explored mechanisms of drug resistance and has been related to a poor response to chemotherapy in several human tumors. Nevertheless, a careful analysis of the literature on MDR1 expression in multiple myeloma (MM) shows the existence of disturbing discrepancies as regards both the incidence of MDR1 over-expression and its clinical value. A prerequisite for the assessment of MDR1 in tumor cells should be the identification of the neoplastic cells present in the sample. This is particularly important in MM, where the percentage of tumor cells in bone marrow (BM) is relatively low. In the present study we have analyzed the functional expression of MDR1 in BM plasma cells (PC), from a group of 40 untreated MM patients. For that purpose, the rhodamine 123 efflux assay was used in combination with specific staining for plasma cells (CD38 strong+). The mean fluorescence channel (MFC) of rhodamine 123 in myelomatous PC from MM patients was 311 and 110 after incubating cells with this fluorochrome for 15 and 60 min, respectively. The median percentage of rhodamine 123 elimination by BM PC was of 61% (range: 0.29 to 88%). Upon analyzing the relationship between the ability of myelomatous PC to eliminate rhodamine 123 and other clinical and biological disease characteristics we found that, within the group of patients displaying high MDR1 expression (>61% rhodamine efflux), there was a higher incidence of cases with bone disease (P = 0.014) and advanced clinical stages (P = 0.031), greater calcium (P = 0.007) and creatinine serum levels (P = 0.061), and lower levels of albumin in serum (P = 0.015). All these parameters are usually associated with a poor prognosis. When we analyzed the possible relationship between the ability of BM PC to eliminate rhodamine 123 and the presence of numerical chromosome abnormalities we observed that a low MDR1 expression was related to a higher incidence of trisomies of chromosomes 6 and 17, although these differences did not reach statistical significance (P = 0.06). In spite of these associations, from the prognostic point of view, MDR1 expression did not correlate with other relevant prognostic factors, response to treatment (P = 0.38) or overall survival (P = 0.12).     

Total and local changes in the arthritis adjuvans

Arthritis adjuvans was studied in the murine model. An effect of different treatment (methotrexate, tauredon, collagen hydrolysate) was estimated in the course of developing disease (day 3, 5, 11 and 21). Repeated evaluation of body weight and peripheral blood leukograms as a total response of organism was performed. Oedema of paw periarticular and tail regions, light- and electron-microscopical screening and immunohistochemical investigation of prevalence of interleukin-1-beta (IL-1beta) and tumour necrosis factor (TNF-alpha) were estimated. The most pronounced benefit effect of methotrexate at stabilization of the monocytes blood level, synovial membrane cell invasion and TNF-alpha immunopositivity was ascertained.     

Rapid detection of Salmonella in field samples by nested polymerase chain reaction

A simple and universal protocol for the rapid detection of Salmonella spp. in various samples using nested polymerase chain reaction (PCR) was developed. The protocol takes advantage of the rapid purification and concentration of Salmonella by centrifugation onto a layer of 60% sucrose solution. DNA was released by treatment with proteinase K and Triton X-100. Even without pre-enrichment, the detection limit for the nested PCR was 10(5) CFU g-1 of faeces. After pre-enrichment, it was possible to detect Salmonella in faeces where their original concentration was approximately 10(2) CFU g-1 of faeces and in meat samples, it was possible to detect Salmonella in samples where their original concentration was less than 10 cells g-1 of minced meat.     

Immunohistochemical evidence of the presence of aromatase P450 in the rat hypophysis

In order to analyze whether aromatase is present in the hypophysis of adult rats, we have performed an immunohistochemical study in young adult male and female rats. Our study has revealed that the hypophysis of adult rats contains aromatase, although marked differences are found between the sexes. The hypophyses of male rats have cells immunoreactive for the enzyme, 34.40% of these hypophyseal cells showing reaction. By contrast, cells from female rats show very little reaction, only 0.84% of them being reactive. No significant differences in the percentage of immunoreactive cells between one phase and another are observed during the estrous cycle. Our results point to the immunohistochemical expression of aromatase in the hypophysis of adult rats and at the same time suggest that its expression is sex-dependent. The enzyme may therefore be involved in the regulation of adenohypophyseal cytology by androgens.