Complexity of RNA in Eggs of DROSOPHILA MELANOGASTER and MUSCA DOMESTICA

Comparative measurements are presented of the sequence complexity of the RNA stored in the eggs of two dipteran flies, Musca domestica and Drosophila melanogaster. The genome of Musca is about five times the size of the Drosophila genome and contains about 3.6 times as much single-copy sequence. As shown earlier, the interspersion of repetitive and single-copy sequence is of the short-period form in Musca, and is of the long-period form in Drosophila. The egg RNA complexities were determined by hybridization of excess RNA with radioactively labeled single-copy DNA. Complexity is expressed as the length (in nucleotides) of diverse single-copy sequence represented in the RNA. The complexity of the RNA of the Musca egg is about 2.4 x 10⁷ nucleotides, and that of the Drosophila egg is about 1.2 x 10⁷ nucleotides. The RNA of the Musca egg is similar to or very slightly lower in complexity than that of other egg RNAs, e.g., those of Xenopus and sea urchin. Compared to all previously measured egg RNAs, Drosophila egg RNA is low in sequence complexity.     

Lectin-mediated sperm agglutination of bufo arenarum and leptodactylus chaquensis spermatozoa

Various plant lecins were employed in cell agglutination experiments to ascertain the presence of specific saccharides in the surface of B arenarum and L chaquensis spermatozoa. B arenarum spermatozoa were specifically agglutinated with Concanavalin A (Con A), phytohemagglutinin P (PHA-P), and wheat germ agglutinin (WGA), but not with soybean agglutinin (SBA). In contrast, L chaquensis spermatozoa were strongly agglutinated by SBA, WGA, and PHA-P. L chaquensis spermatozoa did not agglutinate with Con A even at high concentrations. Lectinmediated sperm agglutination was inhibited in the presence of specific lectinbinding sugars. Spermatozoa from both species were agglutinated randomly with all lectins suggesting a uniform distribution in the sperm surface of the lectinbinding saccharide ligands. B arenarum sperm agglutination induced by Con A is sensitive to temperature. B arenarum spermatozoa are more agglutinable at 24°C than at 4°C. These results suggest that lectin-binding site mobility is necessary for sperm agglutination.     

Succession,diversité et amplitude de niche dans les påturages du centre de la péninsule ibérique

Some diversity and niche amplitude parameters were applied to rangeland pastures of the Central Iberian Peninsula and to their succession stages after the periodical ploughing typical of the traditional management of these areas. Four different slopes within a large area of undulating terrain were selected for the monitoring of succession as they contained the characteristical geomorphological pattern of the area (denudation, transport and accumulation sectors).If we consider the total entropy theorem, H (E.P.)=H(E)+H(P/E), the total entropy of the slope H(E.P) and the entropy of species H(E) increase as succession progresses. As the value of the entropy of the sampling plots conditioned by the species H(P/E) is affected by the number of plots utilized, we employed the expression A=H(P/E)/log₂ number of plots, similar to Pielou's index for niche amplitude, W=H(P/E)/H(P).This values decreases with succession, indicating that plant species tend to occupy more definite sectors along the slope. The number of low entropy species H(P/E) _i or specialist species, confined to narrow sectors also increases. When computed separately within the different sectors niche amplitude results in small values for the low slope regions (accumulation sector). This effect becomes more pronounced when succession advances.

Nous remercions le Conseil d'Administration de La Paranza, propriétaire du Castillo de Vañuelas, et particulièrement Mrs. C. Hernandez-Ros et J. A. Léon-Vrquijò, pour les faeilités qu'ils ont données à cette équipe durant la réalisation de ce travail.     

Isoform-specific subcellular targeting of glucose transporters in mouse fibroblasts

GLUT1, the erythrocyte glucose transporter, and GLUT4, the adipose/muscle transporter, were each expressed in NIH-3T3 cells by retrovirus-mediated gene transfer. In fibroblasts overexpressing GLUT1, basal as well as insulin-stimulated deoxyglucose uptake was increased. Expression of GLUT4 was without affect on either basal or hormone stimulated hexose uptake. Localization of each of the transporters by indirect immunofluorescence revealed that, whereas GLUT1 was found primarily on the cell surface, GLUT4 was directed to vesicles in a perinuclear distribution and throughout the cytoplasm. The GLUT4-containing compartment represented neither Golgi complex nor lysosomes, as evidenced by the failure of lgp110 or Golgi mannosidase to co-localize. However, there was substantial overlap between the distribution of GLUT4 and the transferrin receptor, and some colocalization of the transporter isoform with the manose-6-phosphate receptor. In addition, when FITC-wheat germ agglutinin bound to the cell surface was allowed to internalize at 37 degrees C, it concentrated in vesicular structures coincident with GLUT4 immunoreactivity. These data establish that GLUT1 and GLUT4 contain within their amino acid sequences information which dictates targeting to distinct cellular compartments. Moreover, GLUT4 can be recognized by those cellular factors which direct membrane proteins to the endosomal pathway.     

Tradescantia-micronucleus (Trad-MCN) bioassay on clastogenicity of wastewater and in situ monitoring.

The Tradescantia-micronucleus (Trad-MCN) bioassay was used to determine the clastogenicity of wastewater samples collected from the Arena canal which contains effluent from the industrial district Benito Juarez of the city of Queretaro, Mexico. Fifteen wastewater samples which were collected, in most cases, at bi-weekly intervals beginning in September 1986 through February 1988, after a 3-fold dilution were used to treat Tradescantia plant cuttings. The clastogenicity expressed in terms of micronucleus frequencies of treated groups (30 h of treatment without recovery time) was significantly (0.01) higher than that of the tapwater control groups. The Trad-MCN bioassay was also used for in situ monitoring of air pollutants for the clastogenicity at 3 sites near the industrial and residential areas (Flores Magon, Conalep and Bellas Artes) of the city of Queretaro. Fourteen monitoring trips were made to each of the 3 sites at monthly intervals beginning in May 1988 through June 1990. Seasonal variation of micronucleus frequencies was exhibited with the peak clastogenicities shown in May and June 1988, June 1989 and April 1990 at the three sites. Micronucleus frequencies of all the exposed groups at the Conalep site, a predominantly industrial area, were markedly higher than that of the laboratory control groups throughout the 2-year period.     

Effect of brain serotonin on the arterial pressure and plasma renin in normal and hypertensive rats]

The effects of changes in brain serotonin content after injections of p-chlorophenylalanine (p-CPA), L-5-hydroxytryptophan (L-5HTP) and 5-6-dihydroxytryptamine (5-6DHT) on the mean arterial pressure (MAP), plasma renin activity (PRA) and peripheral levels of atrial natriuretic peptide (ANP) have been studied in normal and hypertensive (2K:1C model) male Wistar rats. The p-CPA (250 mg/kg) and L-5HTP (200 mg/kg) were injected i.p., while 5-6 DHT (15 micrograms/animal in 10 mu/animal vehicle) was injected into lateral brain ventricles. The effects were studied 24 h after the p-CPA injection, 2 h after L-5HTP and 10 or 20 days after 5-6DHT administration. The fall in brain serotonin produced by p-CPA and 5-6DHT did not modify the MAP values in the normal and hypertensive rat model, whereas the increase induced after L-5HTP injection only caused a slight decrease in arterial pressure in normotensive animals. The ARP experimented remarkable rises in the normal and hypertensive rats, these values increasing after L-5HTP and falling after p-CPA and 5-6 DHT injections. Similar changes are detected in the normal group after administration of these substances related to serotoninergic brain activity. The ANP levels rose after renal artery constriction, and they are not affected by the above mentioned substances. Only p-CPA and 5-6DHT reduced a low decrease in the ANP levels 10 days after their administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Changes in somatostatin-like immunoreactivity in lungs from perinatal guinea pigs and the effects of somatostatin-14 on lung liquid production.

Somatostatin-like immunoreactivity was measured by radioimmunoassay with a monoclonal antibody in lungs from perinatal guinea pigs (62 +/- 2 days of gestation). Fetuses delivered by Caesarean section and dissected before breathing showed 4748 +/- 758 pg/lung (n = 25). Fetuses allowed to breathe (neonates) showed marked increases in activity: 7629 +/- 1355 pg/lung (n = 12) after breathing 30 seconds, and 10729 +/- 1064 pg/lung (n = 6) after breathing 3 minutes (2.3-fold increase, P < 0.005). Values then declined (5203 +/- 1050 pg/lung (n = 9) at 30 minutes; 1458 +/- 105 pg/lung (n = 4) at 60 minutes). Changes were similar in pg/g wet tissue. HPLC characterized the immunoreactive peptides as somatostatin-14 (SS-14) and somatostatin-28 (SS-28) in both fetuses and neonates (n = 11). SS-28 made up only 13.7 +/- 1.7% of the activity; this percentage did not change with breathing. The effects of synthetic SS-14 on lung liquid production were investigated in in vitro lungs from 42 fetal guinea pigs. All 21 preparations immersed in 10(-5)-10(-7) M SS-14 during the middle hour of 3 h incubations reduced production, often approaching zero after treatment (rates, ml/kg body weight per h, succeeding hours: 10(-5) M (n = 9), 3.09 +/- 0.68, 0.93 +/- 0.39, -0.05 +/- 0.60 (fall significant during and after treatment, P < 0.025-0.005); 10(-6) M (n = 6), 3.06 +/- 0.68, 1.29 +/- 0.58, 0.36 +/- 0.38 (P < 0.05-0.005); 10(-7) M (n = 6), 1.96 +/- 0.66, 1.11 +/- 0.34, 0.64 +/- 0.28 (P < 0.05-0.025).(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic variability in Muscari comosum L. (Liliaceae) IV Geographical distribution and adaptive role of the polymorphic variants of chromosome 2

Muscari comosum L. (Liliaceae) has a chromosomal polymorphism for a pericentric inversion and a supernumerary chromosome segment probably due to an unequal interchange or insertional translocation. Both arrangements are widely distributed throughout the species range and the mean genetic distance among populations is D=0.131±0.075. There are no correlations between genetic distance and geographic distance or latitude. Only appreciable decreases in the frequencies of the inversion are detected in populations with ecologically marginal characteristics. There is a permanent and extended association between chromosomal inversion and an enzymatic locus (ADH). An excess of individuals heterozygous for the inversion was found and female productivity of heterozygotes is higher than that of corresponding homozygotes. A low rate of inversion heterozygosity in populations with ecologically marginal characteristics could be explained by natural selection. With respect to the adaptive role of the segment, although no homozygotes are found and may be selected against, heterozygotes could have heterotic effects.     

Fluid production by in vitro lungs from fetal guinea pigs

Lungs from fetal guinea pigs (54-67 days of gestation) were supported in vitro, and lung liquid secretion rates were measured by a dye-dilution technique. The average secretion rate in the first hour was 2.14 +/- 0.08 (SE) mL x kg-1 body weight.h-1 (0.21 +/- 0.01 mL/h) (n = 450); this was comparable to intact preparations. In an independent study of 30 lungs, secretion continued unchanged for 3 h, with no significant change in fluid composition. Between 54 days and term, production appeared to fall in terms of millilitres per kilogram per hour. The following agents were placed in the supporting saline during the middle hour of incubation. (i) Sodium iodoacetate: at 10(-4) M this produced a fall in secretion (fall, succeeding hours; 55.4 +/- 23.0 and 64.9 +/- 17.5%; n = 6); at 10(-3) M it stopped secretion (fall, succeeding hours; 87.2 +/- 10.3 and 100%, n = 6). (ii) Ouabain: at 10(-5) M there was no change in production (n = 6); at 10(-4) M, four preparations were unaffected, two reduced production. (iii) Epinephrine (10(-7) M) produced a significant fall in production in all cases (n = 6); in four preparations secretion reduced (average fall, 64.4 +/- 10.8%); in two preparations there was reabsorption (average rate, -1.03 mL.kg-1.h-1). This extends the effect of epinephrine to the guinea pig, and suggests that the in vitro preparation is a useful model for studies of the fetal lung.