Germination response to temperature,salinity, light and depth of sowing of ten tropical dune species

This study describes the germination responses of ten tropical dune species to several factors to which their seeds are exposed in the field. Species studied were: three sand dune endemics (Amaranthus greggii, Palafoxia lindenii, and Trachypogon gouini), three pantropical coastal species (Sesuvium portulacastrum, Sporobolus virginicus and Ipomoea stolonifera) and four cosmopolitan grasses also found inland (Panicum repens, Panicum maximum, Pappophorum vaginatum and Andropogon glomeratus). Six species germinated when exposed to different constant temperatures. Four required temperature fluctuation (S. portulacastrum, P. lindenii, S. virginicus, P. repens). Light promoted germination of three species (S. Portulacastrum, P. vaginatum, P. lindenii). Species varied in their degree of sensitivity to salinity. Seeds of T. gouini, I. stolonifera, S. portulacastrum, P. repens, P. Maximum and P. vaginatum were able to germinate under some of the salinity concentrations. Not all species were able to recover after being transferred to distilled water. Seedling emergence was inhibited when seeds were buried. This response was related to depth and to seed size. S. portulacastrum and S. virginicus were the most affected. Nitrates only affected germination response of two species. Seed age promoted germination under a wider range of conditions. P. lindenii showed very heterogeneous responses depending on seed cohort. No dormancy mechanisms were found, other than a thermoperiod and/or light requirement for some of the species. Cosmopolitan grasses tolerated both sand burial and salinity, although the endemics were the most successful in emerging from sand burial; coastal pantropicals were very tolerant to high saline concentrations and recovered completely.     

Purification and Properties of Glyoxysomal Cuprozinc Superoxide Dismutase from Watermelon Cotyledons (Citrullus vulgaris Schrad)

A glyoxysomal copper,zinc-containing superoxide dismutase (EC 1.15.1.1) was purified to homogeneity, for the first time, from watermelon cotyledons (Citrullus vulgaris Schrad.). The stepwise purification procedure consisted of acetone precipitation, batch anion-exchange chromatography, anion-exchange Fast Protein Liquid Chromatography and gel-filtration column chromatography. Pure copper,zinc-superoxide dismutase (Cu,Zn-SOD II) had a specific activity of 1211 units per milligram protein and was purified 400-fold, with a yield of 8 micrograms enzyme per gram cotyledon. The glyoxysomal Cu,Zn-SOD had a relative molecular weight of about 33,000 and was composed of two equal subunits of 16,500 Daltons. Metal analysis showed that the enzyme, unlike other Cu,Zn-SODs, contained 1 gram-atom Cu and 1 gram-atom Zn per mole dimer. No iron and manganese were detected. Ultraviolet and visible absorption spectra were reminiscent of other copper,zinc-superoxide dismutases.     

Effect of the VAM fungus Glomus sp. on the growth and yield of soybean inoculated with Bradyrhizobium japonicum

The effect of two Bradyrhizobium japonicum strains (D344 and Urbana), on the frequency and intensity of infection by a VAM fungal Glomus sp. and the effect of VAM on biomass production by nodulating plants were tested in soybean growing in a soil containing low levels of accessible P and N. During the initial stage of vegetative growth, mycorrhiza frequency in roots inoculated with the two rhizobial strains did not differ. However, during flowering it was 178% higher in roots with the strain D344 than in the presence of the strain Ubrana. At final harvest (green pods) the VAM frequency did not differ in the presence of either strain. VAM positively affected biomass production, foliar concentrations of P, Zn and Cu, and number and dry matter yield of pods, but did not increase concentrations of total N and K. In nonmycorrhizal plants total nitrogenase activity (not nodule mass) and growth were higher with the rhizobial strain Urbana. The greatest nitrogenase activity, growth and yield occurred in the presence of the VAM fungus, and did not differ for plants with different strains of rhizobia.     

Evaluation of host and pathogen responses for screening soil amendments to control Sclerotium rolfsii

Three strains of Bradyrhizobium, 280A, 2209A and 32H1, that nodulated peanuts (Arachis hypogaea L.), were tested for their ability to grow and survive at elevated temperatures of up to 42°C in laboratory culture. Strain 32H1 was unable to grow at 37°C and was more sensitive to elevated temperatures than the other two strains. All three produced heat-shock proteins of molecular weights 17 kDa and 18 kDa. Two greenhouse experiments were conducted to determine the effect of high root temperature on nodulation, growth and nitrogen fixation of peanut. Two peanut varieties (Virginia cv NC7 and Spanish cv Pronto) were inoculated and exposed to root temperatures of 30°, 37° and 40°C. Nodulation and nitrogen fixation were strongly affected by root temperature but there was no variety × temperature interaction. At a constant 40°C root temperature no nodules were formed. Nodules were formed when roots were exposed to this temperature with diurnal cycling but no nitrogen fixation occurred. Highest plant dry weight, shoot nitrogen content and total nitrogen were observed at a constant root temperature of 30°C. Increasing root temperature to 37°C reduced average nitrogen content by 37% and total nitrogen by 49% but did not reduce nodulation. The symbiotic performance of the strains corresponded to their abilities to grow and survive at high temperature in culture.     

Muscle cell growth in protein deficient rats following administration of sheep red blood cells.

In order to observe the effects of sheep red blood cells (SRBC) administration on the muscle cell growth in malnourished states, adult male Wistar rats (135 +/- 10 g 10 animals per group) subjected during 30 days to 1% and 10% protein diets, were injected (i.v.) either 15.5 x 10(8) sheep red blood cells or 0.5 ml saline/100 g b.w. after 20 days of experiment. On the 10th day after injection the animals were sacrificed and the gastrocnemius muscle was removed, weighed and homogenized. The supernatant fluids were used to evaluate muscle protein, DNA and RNA rates and acid DNase activity. All parameters were depleted in malnourished rats, indicating a muscle cellular atrophy as well as a decrease in muscle protein synthesis per DNA-unit. Muscle hyperplasia and hypertrophy were found in antigenically stimulated rats fed 10% protein against non-stimulated control. In contrast, muscle growth in protein-deficient rats SRBC-treated was unmodified when compared to non-stimulated malnourished muscle, although RNA functionality seems to be enhanced (RNA/DNA). These data suggest that a redistribution of essential nutrients occurred for muscle growth adaptation rather than for defensive mechanism.     

Endocrine cells and nerves in the stomach of the lizard Podarcis hispanica detected by immunocytochemistry

The general identification of endocrine cells in the stomach of the lizard Podarcis hispanica was carried out by their response to the Grimelius and Masson-Fontana techniques. 11 immunoreactive cell-types, positive for chromogranin-, serotonin-, caerulein/gastrin/ cholecystokinin (CAER/G/CCK)-, glucagon-like-peptide-1 (GLP-1)-. glucagon-, bombesin-,somatostatin-, pancreatic polypeptide (PP)-, peptide tyrosine tyrosine (PYY)-, neurotensin-and calcitonin gene related peptide (CGRP)- antisera were detected by immunocytochemical methods. Co-existence of glucagon with GLP-1, and PP with PYY were observed in some cells. Furthermore, immunoreactivities for members of gastrin and PP families were also found to co-exist in a few cells. In the muscular layer, vasoactive intestinal peptide (VIP)- and substance P-immunoreactive nerve fibers were also found.     

Rapidly recurring cortical seizures induce changes in neuronal responsiveness to acetylcholine.

The majority of mechanisms proposed to explain epileptic discharge suggest an excessive synaptic input into the cell or possible changes in cellular excitability which result in a decreased firing threshold and in the presence of self-sustained activity. It is likely that these changes are caused by modifications in the membrane receptor sensitivity to a specific neurotransmitter. In view of the above, the purpose of the present study has been to evaluate the sensitivity of the postsynaptic receptor by means of the microiontophoretic applications of substances whose pharmacological effect is known, thus determining its possible involvement in the epileptic process. Changes in cortical excitability were induced by electric stimuli in the sensorimotor cortex of rats anesthetized with urethane (1 g/kg intraperitoneally), immobilized with pancuronium bromide and kept alive with mechanical respiration. The electric stimuli consisted of trains of biphasic pulses, each lasting one millisecond, with a frequency of 100 pps and with a train duration of 1 second. The response of the neuron to acetylcholine was evaluated before and after the kindling had been established. The dosage was measured in nanoamperes of microiontophoretic ejecting current. Extracellular field potentials were recorded with the central barrel of 4-barrel micropipettes. Peripheral barrels were used for iontophoretic applications of Acetylcholine (Ach .1, 1M), Atropine (25mM). One of these barrels containing NaCl (2M) was used for the automatic passage of balancing current.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro fertilization of intact sheep and cattle oocytes with goat spermatozoa

In an earlier study we reported on the fertilization of in vitro-matured bovine oocytes by ram spermatozoa. The present results extend those observations and demonstrate the penetration of bovine and ovine oocytes matured in culture by goat spermatozoa. Freshly ejaculated and in vitro capacitated goat spermatozoa penetrated 37.1% of bovine and 48.1% of ovine intact oocytes. Monospermic fertilization was detected in about 90% of the oocytes of both species, and the development of pronuclei followed a developmental pattern similar to that of homologous fertilization.     

Use of triple stain technique for simultaneous assessment of vitality and acrosomal status in boar spermatozoa

The object of this study was to adapt the triple stain technique to diluted and incubated boar spermatozoa. Freshly ejaculated semen was resuspended in MR-A diluent to contain 3x10(7) cells/ml (diluted spermatozoa) and was subsequently capacitated (incubated spermatozoa). Experiments were conducted to show the conditions required for optimal staining quality and validation of triple stain technique. The most satisfactory staining solutions for diluted spermatozoa were 2% Trypan blue at 37 degrees C for 15 minutes, 0.8% Bismarck brown in 30% ethyl alcohol (pH 2.8) at 40 degrees C for 10 minutes and 0.8% rose Bengal in 0.1 M of Tris (pH 4.3) at 21 degrees C for 20 minutes. Satisfactory results were obtained for incubated spermatozoa with rose Bengal when the staining time was 10 minutes. Triple stain technique seemed to be a useful method for the simultaneous assessment of sperm vitality and acrosomal status; consequently, it should be valuable tool, for use in porcine in vitro fertilization systems.     

Platinum complexes of p- and m-aminobenzamidine. Synthesis, characterization, and cytotoxic activity.

Four platinum(II) aminobenzamidine complexes have been prepared and characterized by IR and 1H and 13C NMR spectroscopy, and tested for their ability to interact with the nicked and closed circular forms of the pUC8 plasmid DNA. The results show that the complexes of formula [Pt(LH)2Cl2]2X have a cis- geometry with an amino-Pt bonding, where L is either p- or m-aminobenzamidine and where 2X is 2Cl- or PtCl4(2-). It was observed that these complexes significantly alter the electrophoretic mobility of nicked and closed circular forms of DNA and that the alteration in electrophoretic mobility due to Pt(II)-p-aminobenzamidine binding is higher than that due to Pt(II)-m-aminobenzamidine. No difference in mobility was observed whether the DNA interacted with complexes having as counteranion Cl- or PtCl4(2-). The synthesized compounds were, in addition, assayed for antitumor activity in vitro against colon (CX-1), lung (LX-1), and mammary (MX-1) human tumor cells. The results show that these complexes inhibited the multiplication of the tumor cells and that they show higher specificity for lung cells.