The myelodysplastic syndrome: prognostic factors in relation to the "in vitro" clonogenic assay.

The object of this study was to determine whether the "in vitro" parameters of medullary and blood granulopoiesis in patients with MDS, furnish information of either prognostic or diagnostic value. This study covered 94 patients with MDS. All patients were studied at the onset of disease. In order to identify the factors related to patients' survival, Cox Multiple Regression analysis was performed by the BMD P2L program. When analyzing by means of actuarial curves the survival probability of patients with benign development versus those of malignant development (those who developed ANLL), the significance between both groups was p = 0.0001. Different variables of patients included in this study were analyzed and all showed great significances. Fab: p = 0.0022, disease evolution: p = 0.0001 and presence of blastic aggregates: p = 0.0011. Cox's regression analysis revealed that the only predictable survival variable is the presence of blastic colonies and/or clusters. Accordingly, two groups were constructed: favourable and unfavourable. In the favourable group, 40% of the patients belonged to the RA group, while in the unfavourable group, 55% belonged to the RAEB group. This study shows the validity of the elaboration of prognostic groups in MDS according to the presence of blastic colonies and/or clusters in CFUGM medullary and/or peripheral cultures. The "in vitro" myeloid progenitors culture techniques may therefore be advantageously applied in these disorders for formulating a diagnosis and predicting the patient's short term evolution.     

Stabilization of a plasmid-encoded LacZ phenotype inBacillus subtilis

Recombinant plasmid pCED3 was structurally unstable inBacillus subtilis cultures grown in the presence of kanamycin to eliminate the effects of segregational instability. Analysis of 96 modified plasmids indicated that deletions in the plasmid occur at many different sites. The presence of plasmid pCED3 slowed the growth rate of theB. subtilis host. Cells that contained modified plasmids grew faster than the parental cells and took over the population. Two different methodologies were developed to reduce the cultural instability of the plasmid-directed LacZ⁺ phenotype. By growing the cells in a medium that supports a low growth rate, the growth rate ratio between modified and parental cells was reduced, resulting in a partial stabilization (40 generations) of the LacZ⁺ phenotype in the population [35]. Removal of a 4.77 kbEcoRI fragment (which consists primarily of the pBR322 replicon) from plasmid pCED3 produced a more stable plasmid derivative, designated pYS1. Cells harboring plasmid pYS1 grew faster than pCED3-bearing cells, although the level of activity of -galactosidase was similar in both strains. By combining the two approaches (i.e., growth of pYS1-bearing cells in a medium that supports low growth rate), the LacZ⁺ phenotype was stably maintained in the cell population for over 170 generations. Under these conditions, there was no detectable difference between the growth rates of cells bearing the pYS1 plasmid and further modified plasmids.     

Mating behavior of male deer ticksIxodes dammini (Acari: Ixodidae)

To analyze the sexual behavior of male black-legged deer ticks Ixodes dammini,we collected ticks infesting 202 white-tailed deer. On average, 17.7 males and 8.8 females infested each deer. Field-collected males copulated with a mean of 2.25 females, and virgin males mated with 2.4 females. On experimental hosts, males established sexual contact with feeding females and repelled other males, and about half remained paired after their mate detached. Engorged females continue to be receptive, and males mate more readily with them than with nonfed females. We conclude that male I. damminiare endowed with a repertoire of behaviors which favor an opportunistic mating before seeking a host and a preference for mating with feeding females on the host accompanied by tenacious mate guarding.     

Stable assembly of PsaE into cyanobacterial photosynthetic membranes is dependent on the presence of other accessory subunits of photosystem I

We studied assembly of the PsaE subunit of photosystem I into photosynthetic membranes of cyanobacterial mutant strains that lack specific photosystem I subunits. Radiolabeled PsaE was incubated with photosynthetic membranes, and their binding and assembly were assayed by resistance to removal by chaotropic agents and proteolytic digestion. PsaE incorporated into the wild-type membranes was resistant to these treatments. In the absence of PsaD, it was resistant to proteolytic digestion, but was removed by NaBr. When the membranes were isolated from a mutant strain in which the psaF and psaJ genes have been inactivated, PsaE assembled in vitro could not be removed. PsaE could associate with the membranes of the strain DF in which the psaD, psaJ and psaF genes have been mutated. However, the radiolabeled PsaE associated with these membranes was removed both by the proteolytic as well as by the chaotropic agents. Characterization of PsaE present in vivo revealed similar results. These observations suggest that PsaD and PsaF/J may interact with PsaE and stabilize it in the photosystem I complex.     

Molecular characterization of salt-stress-associated protein in citrus: protein and cDNA sequence homology to mammalian glutathione peroxidases

A gene encoding for a citrus salt-stress-associated protein (Cit-SAP) was cloned from Citrus sinensis salt-treated cell suspension. The gene, designated csa, was isolated from a cDNA expression library. The partial amino acid sequence of the protein, as well as that deduced from the nucleotide sequence of csa, revealed a considerable homology to mammalian glutathione peroxidase (GP), and to clone 6P229 from tobacco protoplasts. The increased expression of Cit-SAP in NaCl-treated cultured citrus cells and in citrus plants irrigated with saline water, and its similarity to GP, raise the possibility that one of the effects of salt stress in plants may be the increase of the level of free radicals.     

Drought,heat and salt stress induce the expression of a citrus homologue of an atypical late-embryogenesis Lea5 gene

In a search for genes that are induced in citrus cell suspension in response to salt stress, a cDNA clone with high homology to cotton Lea5 gene was isolated. Data base analysis of the protein deduced from the nucleotide sequence indicates that, like in cotton, the protein from citrus contains regions with significant hydropathic character. The gene, designated C-Lea5, is expressed in citrus leaves as well as cell suspension. The steady-state level of C-Lea5 is increased in cell suspension that is grown in the presence of 0.2 M NaCl. This phenomenon is also observed in leaves of citrus plants irrigated with NaCl and in citrus seedlings which are exposed to drought and heat stress. We suggest that the osmotic stress resulted from elevated level of salt is responsible for the increase in the level of C-Lea5.     

Establishment of regional differences in brush border enzymatic activities during the development of fetal mouse small intestine

Summary In order to study the establishment of regional differences in brush border enzymic activities during the development of fetal mouse small intestine we have followed (1) the differentiation of microvilli by morphometry, and (2) the developmental pattern of three brush border enzymes (lactase, glucoamylase and alkaline phosphatase). From day 16 to day 19 of gestation, the height of duodenal microvilli increases 2.4 times on the absorptive cells located near the tip of the villi. During the same period in the upper half of the duodenal villi, the number of microvilli per square m rises by a factor of 2.4 and the microvillous surface area increases by a factor of 5.2. The differentiation of ileal microvilli follows a similar pattern but they are always shorter and less numerous than those of the duodenum. Lactase activity appears at 18 days of gestation; the other two brush border enzymes are first detected at 16 days of gestation. Afterwards all three enzyme activities increase rapidly and a decreasing gradient of activity is established from the proximal to the distal segment of the small intestine. Hence, the structural development of the microvilli and the appearance of brush border enzyme activities occur simultaneously and a proximo-distal gradient is already established at 16 days of gestation.Supported by MRC of Canada research grant MA-6069Mr. D. Malka was supported by a studentship from the F.C.A.C.Dr. D. Ménard is a chercheur boursier du Conseil de la Recherche en Santé du Québec     

Developmental pattern of glucose-6-phosphatase activity in the small intestine of the mouse fetus

Summary The distribution of glucose-6-phosphatase (G6Pase) activity in the epithelium of the small intestine in mouse embryos (the last 4 days of gestation) was studied by electron microscope cytochemistry and by enzymatic assays. At 16 days, the lead phosphate deposited by the cytochemical reaction is localized on the rough endoplasmic reticulum (RER) and nuclear envelope of very few cells in the duodenum and jejunum. Positive cells are more frequently seen in the upper part of the developing villi. At 17 days of gestation, a tremendous burst in RER differentiation is noticed in all parts of the small intestine and concomitantly glycogen disappears. At 18 days of gestation all the principal cells of the intestinal mucosa show a well differentiated positive RER and the enzyme is also present in the smooth endoplasmic reticulum. Biochemically, G6Pase activity is detected in the proximal 2 thirds of the small intestine at 17 days of gestation and appears at 18 days in the last third. Afterwards the activity increases up until birth. These results suggest (1) that the endoplasmic reticulum differentiates very late in the intestinal mucosa of mouse embryos (2) that the differentiation with respect to G6Pase is asynchronous between the enterocytes, (3) that for a given cell all the cisternae of RER are involved in G6Pase synthesis at the same moment and (4) that the enterocytes of the duodenum differentiate sooner and faster that those of the jejunum and ileum.This work was supported by Grant No. 6069 from the MRC of CanadaMr. D. Malka was supported by a studentship from the F.C.A.C. of the province of QuebecDr. D. Ménard is a Chercheur boursier du Conseil de la Recherche en Santé du Québec