Investigation of Homologous Crossing over and Sister Chromatid Exchange in the Wheat Nor-B2 Locus Coding for Rrna and Gli-B2 Locus Coding for Gliadins

Recombination was investigated within the Nor-B2 locus of wheat chromosome 6B that contains several thousand of the 18S-5.8S-26S rRNA (rDNA) repeated units. Additionally, recombination was assessed for several chromosome regions, in arm 6Bq between the centromere and the B2 locus (awn suppressor) and in arm 6Bp between the centromere and Nor-B2, between Nor-B2 and a distal C-band and between Nor-B2 and Gli-B2 coding for gliadins. The experimental design permitted the distinction between crossing over between homologous chromosomes and exchange between sister chromatids. No homologous crossing over within the Nor-B2 locus was found in a sample of 446 chromosomes, but one exchange with the attributes of unequal sister chromatid exchange was identified. The molecular characteristics of this presumed sister chromatid exchange indicate that the spacer variants present in the Nor-B2 locus are clustered. No homologous recombination was detected within the distal Gli-B2 locus containing repeated genes coding for gliadin seed-storage proteins. Both arms of chromosome 6B showed low crossing-over frequency in the proximal regions. The distance from the centromere to Nor-B2 was only from 0.3 to 2.2 cM although it accounts for about two-thirds of the metaphase chromosome arm, which shows a great distortion of the metaphase map of the arm. The level of homologous recombination within the Nor-B2 locus is lower than in the chromosome region immediately distal to it. Whether it is comparable to that in the chromosome region proximal to it could not be determined. Recombination frequencies of different pairs of chromosome 6B in all but one interval paralleled the frequencies of their metaphase I pairing: Lower pairing at metaphase I was paralleled by lower crossing-over frequency. This relationship indicated that reduced metaphase I pairing between 6B chromosomes from different populations is due to impaired crossing-over and not due to precocious chiasma terminalization.     

The species composition,occurrence and temporal stability of submerged aquatic macrophyte patches along the main channel border of pool 5A,Upper Mississippi River

Species composition, relative abundance, distribution and physical habitat associations of submerged aquatic macrophytes in the main channel border (MCB) habitat of Pool 5A, Upper Mississippi River (UMR) were investigated during the summers of 1980 and 1983. The submerged aquatic macrophytes in Pool .5A MCB were a small and stable component of the river ecosystem. Submerged plants occurred primarily in small, monospecific clumps. Clumps in close proximity to each other formed plant patches. Plant patches were stable in location and number between 1980 and 1983; 82.5% of the patches first observed in 1980 were present in 1983. Submerged macrophytes covered about 10–12 ha of the 201 ha MCB in Pool 5A. Submerged plants were most common in the lower two-thirds of the pool. Ten species of aquatic macrophytes occurred on rock channel-training structures and eleven occurred on non-rock substrates in the MCB. The most common submerged plants, in order of abundance, were Vallisneria americana Michx., Heteranthra dubia Jacq., Potamogeton pectinatus L., Ceratophyllum demersum L. and Potamogeton americanus C. & S.     

Trifluoperazine inhibits thyrotropin-releasing hormone-stimulated TSH secretion

In previous work changes of the thyrotropic secretion after administration of some substances affecting the calcium content in the cytosol were demonstrated. The object of the present investigation was to assess the hormonal response to the administration of trifluoperazine, a psychopharmaceutical preparation, the main mechanism of its action being the inactivation of the cytosol receptor for the calcium signal - calmodulin. The poor utilization of intracellular calcium of the secretory cell is then the factor which inhibits secretion proper. The thyrotropic secretory reserve (delta TSH) was assessed in the same subjects before and after trifluoperazine administration by the TRH test as the difference of values at rest and TRH-stimulated TSH levels during the 20th, 30th, 40th and 60th minute following intravenous administration of 200 micrograms TRH. It was revealed that this calmodulin antagonist administered for one week in amounts of 6-12 mg per day by mouth significantly inhibits the secretory response of TSH to TRH in healthy subjects during the 20th and 40th min. (P less than 0.05). The reproducibility of the TRH test repeated in a group of subjects not treated with trifluoperazine, however, under equal conditions and after the same time intervals as in the experiment with trifluoperazine was very satisfactory and thus physiological inhibition caused by repeated TRH administration could be ruled out. The inhibition of the secretory TSH response to TRH can be therefore considered the consequence of the direct effect of trifluoperazine on the thyrotropic secretory mechanism. Trifluoperazine significantly reduced serum calcium levels and raised phosphate levels, while it did not affect the blood levels of magnesium.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of pinealectomy on plasma glucose, insulin and glucagon levels in the rat

In an attempt to know the role of the pineal gland on glucose homeostasis, the blood plasma concentrations of glucose, insulin and glucagon under basal conditions or after the administration of nutrients were studied in the jugular vein of conscious pinealectomized (Pn), melatonin-treated pinealectomized (Pn + Mel) and control (C) rats. Glucose levels were smaller in C than in Pn rats, while immunoreactive insulin (IRI) concentrations were significantly greater in C than in Pn rats. Contrary to this, immunoreactive glucagon (IRG) levels were significantly greater in Pn than in C animals. Melatonin treatment of Pn rats induces an increase of IRI concentrations and a reduction in IRG levels. Similar changes were obtained when hormonal determinations were carried out in portal blood plasma. Although ether anesthesia increases circulating glucagon levels in the porta and cava veins, the qualitative changes of plasma insulin and glucagon in Pn and Pn + Mel were similar to those found in conscious rats. To determine the effects of nutrients on pancreatic hormone release, intravenous arginine or oral glucose were administered to the animals of the three experimental groups. In C rats, both glucose and IRI levels reached a peak 30 minutes after glucose ingestion, decreasing thereafter. However, in Pn rats a glucose intolerance was observed, with maximum glucose and insulin concentrations at 60 minutes, while in Pn + Mel animals, glucose and IRI concentrations were in between the data obtained with the other two groups. Furthermore, glucose ingestion induced a significant reduction of IRG levels in all the groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphine induced thyroxine release from rat thyroid gland in vitro

Male rat thyroid glands were incubated for two hours in Krebs-Ringer bicarbonate buffer with different amounts of morphine and/or naloxone. Five micrograms/ml morphine produced a significant increase in the T4 concentration of incubation medium, and resulted in an accumulation of cAMP in the tissue. Naloxone did not change the T4 release but its incubation with morphine prevented the morphine-induced changes. Similarly, naloxone inhibited the morphine-induced accumulation of cAMP in the thyroid tissue.     

The Pleistocene lake deposits of the NE Baza Basin (Spain): salinity variations and ostracod succession

The Guadix-Baza Basin in Spain covers an area of approximately 3000 km² and yields a sedimentary sequence ranging from Lower Miocene to Pleistocene. Twenty five meters of Lower Pleistocene lacustrine sediments have been located in the NE part of the Basin at about 1000 meters in altitude. This sequence which overlies dolomitic mud flat deposits consists of limestones, calcareous and dolomitic mudstones, dolostones, silty clays, sands and gravels. Salinity fluctuations and short dry episodes, related to lake level oscillations, have been recorded by textural, mineralogical and faunal changes throughout the sequence. Ostracods, which are the most commonly encountered fossils, permit to detect recurrent changes in water salinity and regime, and solute composition. The faunal changes indicate an alternation of slightly saline and bicarbonate-rich water (when ostracods and gastropods occur) with a saline NaCl-dominant water (in which ostracods, Cerastoderma bivalves and non-marine foraminifers are found).The frequent and recurrent hydrochemical changes in the Baza Basin in the Early Pleistocene point to a climate of high contrast like in the Mediterranean region today but with a greater availability of water within the system compared to the present situation in the area.     

Influence of amphetamine-induced changes in the behavior of adult "aunts" on development and long term behavioral patterns of rats

Infant rats of the Wistar strain were kept either with their mother or with both the mother and the "aunt"--an adult virgin female during the suckling period. One group of aunts was injected regularly with amphetamine in the dose of 3 mg/kg b.w. (the AA group), another group with saline (the SA group). Control (CO) pups were reared by their mother only. Both acute and long term consequences of aunt-rearing on behavioral development and growth rate were observed. On Days 25 and 28 the SA pups displayed an increased exploratory activity level and more contacts with the litter-mate in the test of paired interactions when compared with both the AA and CO groups. The lowest frequency of exploratory, of manipulatory and social activities were recorded for the AA pups. In adulthood, both the aunt-reared groups of male rats exhibited higher activity level in a novel environment than the CO males. However, while in the CO and the SA males the activity level tended to habituate over the repeated tests, in the AA it persisted on a high level. The difference among females was not significant. Growth rate was retarded in the AA male and female rats.     

A set of procedures for resolving purine compounds by reversed-phase high performance liquid chromatography: application to the study of purine nucleotide and nucleic acid metabolism

A set of simple procedures for the separation of major purine 5'-ribonucleotides including diguanosine polyphosphates, purine and pyrimidine bases, and 2'- and 3'-nucleotide monophosphates using reversed-phase high-performance liquid chromatography and isocratic elution study of purine nucleotide and nucleic acid biosynthesis in Artemia is presented.     

Isolation and Characterization of an Fe(III)-Chelating Compound Produced by Pseudomonas syringae

The phytopathogenic bacterium Pseudomonas syringae produces a fluorescent pigment when it is grown in iron-deficient media. This pigment forms a very stable Fe(III) complex that was purified in this form by using a novel procedure based on ultrafiltration and column chromatography. The Fe(III) complex has a molecular weight of 1,100 and contains 1 mol of Fe(III). The pigment is composed of an amino acid moiety with three threonines, three serines, one lysine, δ-N-hydroxyornithine, and a quinoline-type fluorescent chromophore. These features and its stability constant (in the range of 10³²) suggest that the fluorescent pigment of P. syringae is related to the siderophores produced by another Pseudomonas species.