In Vivo and in Vitro Experimental Analysis of Lens Regeneration in Larval Xenopus laevis

After lentectomy of larval Xenopus laevis , the outer cornea undergoes tissue transformation resulting in formation of a new lens. This lens regeneration is triggered and sustained by neural retina. In the present study, lens-forming transformation of the outer cornea was completed in vitro when the outer cornea was cultured within the lentectomized eye-cup. Well-differentiated lens fiber cells, which showed positive immunofluorescence for total crystallins, were also formed when the outer cornea was cultivated with the retina. No lens tissue was formed when the cornea was cultured alone. Lens-forming transformation, originating from the cornea three and five days after lentectomy, completely regressed when the tissue was isolated in vitro . Fom the present and previous findings, we concluded that, the interaction of corneal cells with the retina plays a decisive role in lens regeneration in situ .     

Phenylalanine ammonia-lyase activity in suspension cultures of Ulmus pumila and U. campestris treated with spores of Ceratocystis ulmi

Summary Cell suspension cultures of a Ceratocystis ulmi-resistant (Ulmus pumila) and a -susceptible elm (U.campestris) were established from leaf callus tissue. Treatment of cultures with spores of C.ulmi induced a large increase in the activity of phenylalanine ammonialyase, only in the cells of the resistant species U.pumila with a maximum after 24 h. Inoculated U.pumila cells also excreted a red unidentified chemical into the culture medium. Neither responses were induced in inoculated U.campestris cultures. The results are discussed in relation to the development of the elm cell culture system as a model for studying the differential biochemical mechanisms of disease resistance in elms.     

Forest resistance to drought in a humid tropical dipterocarp forest in the Western Ghats of India

Droughts are linked to tree die-offs in the biodiverse humid tropics. We assessed drought response of a Dipterocarp Forest and found a marginal decrease in tree survival, indicating drought resistance. Understory and emergent species were sensitive to drought. Urgent focus is needed to understand drought impacts and plant physiological responses in South Asian forests.     

Role of puncture and aspiration in expectant management of simple ovarian cysts: a randomised study.

OBJECTIVES: To assess the potential of expectant management for simple ovarian cysts diagnosed by transabdominal or transvaginal ultrasonography. To compare the results of needle aspiration with those achieved with simple observation. DESIGN: Randomised trial. SETTING: Hospital department of obstetrics and gynaecology. SUBJECTS: 278 women with simple cysts randomly allocated to simple observation (143) or ultrasound guided fine needle aspiration (135) between 1990 and 1994. MAIN OUTCOME MEASURES: Resolution of cyst or development of malignancy. RESULTS: After six months 269 were available for follow up. The rate of resolution was 46% (59/128) with aspiration and 44.6% (63/141) with observation. Only the diameter of the cyst (P < 0.0001) was a significant independent prognostic factor for resolution in a multivariate analysis. Age and treatment had no significant effect. One woman was subsequently found to have borderline malignant changes on histopathological examination. Her cyst was detected by transabdominal ultrasonography. CONCLUSIONS: Expectant management for up to six months does not cause risks for the patients and allows spontaneous resolution in over a third of cases, avoiding the costs and risks of unnecessary surgery. Aspiration does not provide better results than simple observation.     

Ehrlich cell plasma membrane redox system is modulated through signal transduction pathways involvingcGMP and Ca2+ as second messengers

Ehrlich cell plasma membrane ferricyanide reductase activity increased in the presence of mastoparan, a generic activator of G proteins, using either whole cells or isolated plasma membrane fractions. Agents that increase intracellularcAMP also increased the rate of ferricyanide reduction by Ehrlich cells. For the first time, evidence is shown on a modulation of plasma membrane redox system bycGMP. In fact, permeant analogs ofcGMP, dibutyrylcGMP, and 8-bromo-cGMP increased the rate of ferricyanide reduction by the Ehrlich cell plasma membrane redox system. Furthermore, specific inhibition ofcGMP-phosphodiesterases by dipyridamole was also accompanied by an enhancement in the rate of ferricyanide reduction. On the other hand, treatments expected to increase cytoplasmic Ca²⁺ concentrations were accompanied by a remarkable stimulation of the reductase activity. Taking all these data together, it seems that the Ehrlich cell plasma membrane redox system is under a multiple and complex regulation by different signal transduction pathways involving G proteins, cyclic nucleotides, and Ca²⁺ ions.     

Pole Cell Migration through the Gut Wall of the Drosophila Embryo: Analysis of Cell Interactions

Early in development the precursors of germ cells in Drosophila migrate at the posterior pole of the embryo and translocate to the bottom of the developing posterior midgut primordium. At the end of germ band elongation the pole cells cross the gut wall to enter in association with the gonadal mesoderm. We used laser scanning confocal microscopy on whole-mount Rh-phalloidin-stained embryos and transmission electron microscopy to investigate how pole cells cross the epithelial wall of the posterior midgut primordium. Our results suggest that pole cells leave the midgut sac by traveling through the intercellular spaces of the epithelium. During this process the epithelial cells at the bottom of the posterior midgut primordium are greatly deformed, but their junctional complexes do not completely release, avoiding breaks in the epithelial wall.     

Life history and species composition of the damselfly assemblage along the urban tract of a river in central Italy

The species composition of the damselfly assemblage and the life history patterns of two Coenagrionidae (Ischnura elegans and Cercion lindeni) were investigated along the urban tract of a river characterized by increasing organic pollution. The assemblage was dominated by generalist species, usually recorded in lentic habitats, rather than by typical riverine species and the proportion of the latter decrease at the most polluted sites. At the end of Winter, the mean size and in star distribution were different between the sampling sites showing that the life history of both species examined were influenced by a degradation of the environmental quality. A longer reproductive period, absence of diapause, and tolerance of low oxygen concentration appear to be key factors that allow generalist species I. elegans and C. lindeni to predominate at the polluted sites. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pyridoxine-responsive gyrate atrophy of the choroid and retina: clinical and biochemical correlates of the mutation A226V.

We discovered the missense mutation, A226V, in the ornithine-delta-aminotransferase (OAT) genes of two unrelated patients with gyrate atrophy of the choroid and retina (GA). One patient, who was a compound for A226V and for the premature termination allele R398ter, showed a significant (P < .01) decrease in mean plasma ornithine levels, following pyridoxine supplementation with a constant protein intake: 826 +/- 128 microM (n = 5; no pyridoxine supplementation) versus 504 +/- 112 microM (n = 6; 500 mg pyridoxine/d) and 546 +/- 19 microM (n = 6; 1,000 mg pyridoxine/d). In extracts of fibroblasts from a second GA patient homozygous for A226V and from Chinese hamster ovary cells expressing an OAT-cDNA-containing A226V, we found that OAT activity increased from undetectable levels to approximately 10% of normal when the concentration of pyridoxal phosphate was increased from 50 to 600 microM. A226V is the fourth disease-causing pyridoxine-responsive human mutation to be reported.