Genetic diversity among exotic cotton accessions as for qualitative and quantitative traits.

Studying genetic diversity among a group of genotypes is important in genetic breeding because identifying hybrid combinations of greater heterotic effect also increases the chance of obtaining plants with favorable allele combinations in an intra-population selection program. The objective of this study was to compare different types of long and extra-long staple cotton and their genetic diversity in relation to the fiber traits and some agronomic traits in order to grant breeding programs. Diversity analysis among 29 cotton accessions based on qualitative and quantitative traits and joint including qualitative and quantitative traits was performed. Analysis based on qualitative and quantitative traits and joint met the accessions in three, two, and three groups, respectively. The cross between genotypes Giza 59 and Pima unknown was the most promising to generate segregating populations, comprising simultaneously resistance (based on molecular markers) to blue disease and bacterial blight, partial resistance to root-knot nematode, smaller size, in addition to good fiber characteristics. These populations can be used in recurrent selection programs as donors of alleles for development of long-staple cotton genotypes.

Genetic gains from selection for fiber traits in Gossypium hirsutum L.

Brazil is among the five largest producers of cotton in the world, cultivating the species Gossypium hirsutum L. r. latifolium Hutch. The cultivars should have good fiber quality as well as yield. Genetic improvement of fiber traits requires the study of the genetic structure of the populations under improvement, leading to the identification of promising parent plants. To this end, it is important to acquire some information, such as estimates of genetic variance components and heritability coefficients, which will support the appropriate choice of the breeding strategy to be employed as well as enable the estimation of gains from selection. This study aimed to evaluate some agronomic characteristics, such as fiber quality and yield, estimating genetic parameters for the purpose of predicting earnings. Twelve cultivars of cotton, including four male progenitors (CNPA 01-42, BRS Verde, Glandless, and Okra leaf) and eight female progenitors (Delta opal, CNPA 7H, Aroeira, Antares, Sucupira, Facual, Precoce 3, and CNPA 8H), were used in performing crosses according to design I, proposed by Comstock and Robinson (1948). The experimental design was a randomized block with four replications. We observed genetic variability among all traits as well as higher efficiency of selection for the gains related to traits. Our results showed that the combined selection presented the highest genetic gains for all traits. For fiber length, the female/male selection and the combined selection resulted in the highest genetic gain.

Effects of combined zidovudine/lopinavir/ritonavir therapy during rat pregnancy: morphological aspects.

PURPOSE: To evaluate the morphological aspects in rats subjected to an association of the antiretroviral drugs zidovudine/lopinavir/ritonavir in different doses administered throughout the gestational period. MATERIALS AND METHODS: Forty pregnant rats were randomly allocated into four groups: control (Ctrl) and experimental (Exp1, Exp2, and Exp3), which received zidovudine/lopinavir/ritonavir in the doses of 10/13.3/3.3, 30/39.9/9.9, and 90/119.7/29.7 mg/kg per day from the first to the 20th day of pregnancy, respectively. At term, the animals were euthanized and maternal and fetal organ samples were removed for morphological analysis. RESULTS: No major changes were identified in the group treated with the lowest dosing compared with the control. In group Exp2, the authors found hepatocytes with eosinophilic cytoplasm, pyknotic nuclei, and vasodilation. The proximal convoluted tubules of maternal kidneys showed eosinophilic areas and hyperchromatic nuclei, as well as signs of vasodilation. In the group treated with the highest dose (Exp3); the morphological changes in the maternal kidneys and livers were similar and more pronounced than those found in Exp2. The maternal pancreas of groups Exp2 and Exp3 evidenced moderate and progressive signs of tissue damage. The morphological features of all fetal livers, kidneys, and pancreases were normal. CONCLUSION: High doses of zidovudine/lopinavir/ritonavir association during the entire rat pregnancy period can cause definite morphological changes in maternal liver, kidneys, and pancreas. On the other hand, the corresponding fetal organs were not affected.

Chronic action of association of zidovudine, lamivudine and ritonavir on pregnant rats. A biologic assay.

PURPOSE: To evaluate at term the effects of a highly active antiretroviral (HAAR) drug association administered during the entire period of rat pregnancy. METHODS: Three groups (n = 10 each) of adult pregnant rats were treated with an oral solution of HAAR (Exp 1 = 10/5/20 mg/kg b.w.; Exp 2 = 30/15/60 mg/kg b.w.; Exp 3 = 90/45/180 mg/kg b.w.) from day "0" up to the 20th day of pregnancy. A fourth group served as a control. At term (20th day) the rats were killed under deep anesthesia and the number of implantations, resorptions, living fetuses, placentae and intrauterine deaths were recorded. RESULTS: The highest HAAR doses caused lower maternal weight gain, lower litter weights, and lower placental weights compared to the control group. CONCLUSIONS: HAAR during the entire period of rat pregnancy can reduce maternal body weight gain and lower term placental weight.

Fast potentiation of glycine receptor channels of intracellular calcium in neurons and transfected cells.

Inhibitory glycine receptors (GlyRs) are mainly expressed in the spinal cord and in the midbrain, where they control motor and sensory pathways. We describe here a fast potentiation of GlyR by intracellular Ca2+. This phenomenon was observed in rat spinal cord neurons and in transfected human cell lines. Potentiation develops in <100 ms, is proportional to Ca2+ influx, and is characterized by an increase in GlyR apparent affinity for glycine. Phosphorylation and G protein pathways appear not to be involved in the potentiation mechanism. Single-channel recordings in cell-attached and excised patches, as well as whole-cell data suggest the presence of a diffusible cytoplasmic factor that modulates the GlyR channel gating properties. Ca2+-induced potentiation may be important for rapid modulation of glycinergic synapses.

The endogenous agonist quinolinic acid and the non endogenous homoquinolinic acid discriminate between NMDAR2 receptor subunits.

Quinolinic acid is an endogenous neurotoxin with NMDA receptor agonist properties. As such it may be the etiologic agent in many diseases. In this paper the NMDA receptor agonist properties of quinolinic acid, as well as those of homoquinolinic acid, a non endogenous analogue, were investigated in Xenopus oocytes injected with 12-day-old rat cortical mRNA or with recombinant NMDA receptors. In oocytes injected with cortical mRNA, quinolinic acid was a weak NMDA receptor agonist: millimolar concentrations were necessary to induce responses that were smaller than maximal responses induced by NMDA; homoquinolinic acid and NMDA had similar affinities but different efficacies: maximal responses induced by homoquinolinic acid were larger than maximal responses induced by NMDA. Cortical mRNA, as verified by RT-PCR and restriction analysis, contains various NMDA subunits. In order to investigate if the low affinity or efficacy of quinolinic acid could be explained by receptor composition, the pharmacological properties of the putative agonists were investigated in oocytes expressing binary combinations of recombinant NMDA receptors. Quinolinic acid did not activate receptors containing NR1 + NR2C but did activate receptors containing NR1 + NR2A and NR1 + NR2B even if only at millimolar concentrations; homoquinolinic acid activated all subunit combinations but was less efficient than NMDA only in the NR1 + NR2C subunit combination. The relative efficacies of quinolinic acid and homoquinolinic acid were evaluated by comparing the maximal responses induced by these agonists with those induced by NMDA and glutamate in the same oocytes. The rank order of potency was quinolinic acid < NMDA < homoquinolinic acid < or = glutamate for the NR1 + NR2A and NR1 + NR2B combinations whereas for NR1 + NR2C it was quinolinic acid << << homoquinolinic acid < NMDA < or = glutamate. The use of quinolinic acid and homoquinolinic acid may thus help to identify endogenous receptors containing the NR2C subunit.

Synthetic routes to 4-amino-3-carboxy-beta-carboline derivatives: incidental formation of novel furo[3,4-c]-beta-carbolin-2-ones displaying high affinities for the benzodiazepine receptor.

The synthesis of the first 4-amino-3-carboxy-beta-carboline derivative (35) is described. This synthesis is based on ozonolysis of the 4-vinyl-beta-carboline-3-carboxamide 17 to give the 4-aldehyde 20 and potassium permanganate oxidation of the latter to the 4-carboxylic acid 34 followed by a DPPA-promoted Curtius rearrangement. During the course of these transformations, a number of furo[3,4-c]-beta-carbolin-2-ones, differing in substituents at the C-10 position, were formed. While these beta-carboline lactones (15,25,26,33) generally displayed good affinities for the central type benzodiazepine receptor in vitro (IC50's in the 10-50 nM range), one compound, 29, demonstrated an exceptionally high binding affinity (IC50 = 0.2 nM). Compound 29 was shown in electrophysiological and behavioral studies to act as a benzodiazepine receptor antagonist. The unusually high binding affinity of compound 29 corroborates the hypothesis that the benzodiazepine receptor preferentially recognizes the C-3 carbonyl function of 3-carboxy-beta-carbolines in an s-cis conformation (i.e., the carbonyl oxygen on the same side as the pyridinyl nitrogen).

Quinoxaline derivatives: structure-activity relationships and physiological implications of inhibition of N-methyl-D-aspartate and non-N-methyl-D-aspartate receptor-mediated currents and synaptic potentials.

The inhibitory potencies at excitatory amino acid (EAA) receptors of 11 quinoxaline derivatives were evaluated in two-electrode voltage-clamp recordings of Xenopus oocytes injected with rat cortex mRNA. Currents activated by kainate or (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) in Xenopus oocytes were inhibited competitively by all the quinoxaline derivatives, with apparent Ki values ranging from 0.27 to 300 microM against kainate and from 0.25 to 137 microM against AMPA. An excellent correlation was observed between inhibitory potencies of the quinoxaline derivatives against kainate and AMPA currents, in support of the contention that in this preparation these two agonists act at a single site. All 11 quinoxaline derivatives also inhibited current activated by the combination of glycine and N-methyl-D-aspartate (NMDA), apparently acting at the glycine site, and did so over a narrower range of apparent Ki values (0.37-8.1 microM). The correlation between the quinoxalines' kainate/AMPA potencies and their glycine/NMDA potencies was relatively weak. Thus, the quinoxaline derivatives were all good antagonists of glycine/NMDA currents and displayed a greater range of potencies against kainate and AMPA. The inhibitory effects of the six quinoxaline derivatives most potent in the Xenopus oocyte experiments were also tested against the excitatory postsynaptic field potential (EPSFP) recorded in the pyramidal cell dendritic field of the CA1 region of hippocampal slices after stimulation of the Schaffer collateral-commissural pathways. In slices superfused with "normal" medium (containing 1 mM Mg2+), in which the EPSFP is mediated primarily by non-NMDA receptors, IC50 values correlated closely with the Ki values against kainate/AMPA obtained in oocyte experiments but were approximately 8-fold higher. Similarly, in slices superfused with nominally Mg(2+)-free medium, in which the EPSFP is amplified due to a relief of the Mg2+ block of NMDA receptors, IC50 values correlated closely with the Ki values against glycine/NMDA obtained in oocyte experiments but were 60-fold higher. This comparison of results from the two experimental systems lends further support to the argument that hippocampal synaptic transmission is mediated postsynaptically by kainate/AMPA-type and NMDA/glycine-type EAA receptors that are pharmacologically indistinguishable from those expressed in mRNA-injected Xenopus oocytes. Furthermore, it suggests that EAA receptors in situ may be nearly saturated by high local concentrations of the endogenous ligands, a condition that would contribute substantially to the apparent non-NMDA receptor selectivity of certain quinoxaline derivatives.

Benzodiazepine impairs and beta-carboline enhances performance in learning and memory tasks.

Benzodiazepines are widely used anxiolytics and anticonvulsants, and their potent sedative properties are routinely used in presurgical anaesthesia. However, they are also known to induce a strong anterograde amnesia in patients. Specific benzodiazepine antagonists have recently been described, some of which have intrinsic pharmacological properties that are opposite to those of benzodiazepines. These have been called inverse agonists and they have been shown to be proconvulsant or convulsant whereas benzodiazepines are anticonvulsants. Inverse agonists are also anxiogenic rather than anxiolytic. Since benzodiazepines induce anterograde amnesia, we have investigated the possibility that inverse agonists might also have an opposite effect for this property and so enhance acquisition (learning) and (or) retention (memory). We report here that, in three different animal models, an inverse agonist of the beta-carboline group, methyl beta-carboline-3-carboxylate (beta-CCM), enhances animal performance in three different tasks used to investigate learning and memory.

3-Amino-beta-carboline derivatives and the benzodiazepine receptor. Synthesis of a selective antagonist of the sedative action of diazepam.

Seven 3-N-substituted derivatives of 3-amino-beta-carboline were synthesized and their affinities for the benzodiazepine receptor were assessed in vitro. Two compounds, 3-(ethylamino)-beta-carboline and 3-[(methoxycarbonyl)amino]-beta-carboline (beta-CMC), showing IC50 values of 460 and 71 nM, respectively, were selected for in vivo studies. The former compound showed long-lasting proconvulsant activity in Papio papio baboons while beta-CMC was shown in mice to selectively antagonize the sedative effects of diazepam without exhibiting convulsant, proconvulsant, or anxiogenic activity by itself.

[Potent convulsant effects of a benzodiazepine inverse agonist, methyl beta-carboline-3-carboxylate in cats].

The convulsant properties of methyl beta-carboline-3-carboxylate (beta-CCM), which is a homologue of a putative benzodiazepine receptor ligand in the mammalian central nervous system, were examined in cats. Subcutaneous injection of 0.5 mg/kg of the beta-CCM produced various degrees of myoclonic jerks always accompanied by cortical spike burst. Some autonomic symptoms such as tachypnea, hypersecretion of thick mucous saliva, vomiting and mydriasis were also presented. Subcutaneous injection of 1.0 mg/kg of the compound induced a generalized tonic-clonic convulsion. Injection of the same amount of the drug 1 hour later in the same cats failed to provoke a generalized seizure. Repeated injection of the same dose 3 hours later provoked a generalized seizure, but with a longer latency. However, repetition of the experiments 24 hours after or 10 days after the first injection consistently induced the same type of generalized seizure with the same latency as the first injections. These results support the suggestion that the pharmacological effect, especially the convulsive effect, of beta-CCM is dose-related, reversible and reproducible in the same cats and among different cats. Moreover, the postictal refractory period in this model of epilepsy may continue about for 3 hours.

Convulsions induced by submaximal dose of pentylenetetrazol in mice are antagonized by the benzodiazepine antagonist Ro 15-1788.

The effects of benzodiazepine antagonist Ro 15-1788, alone or with diazepam, were studied in mice on convulsions induced by pentylenetetrazol (PTZ). We found that Ro 15-1788 (1 mg/kg) was able to antagonize the anticonvulsive effects of diazepam (1 mg/kg), but also had, with submaximal doses of PTZ (65 mg/kg), its own anticonvulsive action. At very low doses (0.1 mg/kg), it even potentiated the anticonvulsive effects of diazepam (0.05 mg/kg). This dual action provides evidence for partial agonist properties of the antagonist Ro 15-1788.

Anxiogenic and non-anxiogenic benzodiazepine antagonists.

Benzodiazepines are widely used anxiolytic and anticonvulsant drugs, and brain receptors for these drugs have been characterized by Möhler and Okada and Squires and Braestrup. Recently, substances that antagonize benzodiazepine binding to brain receptors have been discovered. These benzodiazepine antagonists were shown to block the central effects of benzodiazepines and particularly their anticonvulsive properties. Two such antagonists, Ro 15-1788 (an imidazodiazepine) and methyl beta-carboline-3-carboxylate (beta-CCM), have recently been shown to have different intrinsic pharmacological properties. beta-CCM, injected into baboons, cats, mice and rats, is a convulsant, whereas Ro 15-1788 lacks such an activity. Thus, the separation of convulsant and non-convulsant antagonists has been proposed. We suggest here that a subclassification of antagonists is also valid at the behavioural level, based on a conflict model in mice. We show that Ro 15-1788 and beta-CCM antagonize the anxiolytic effect of benzodiazepines. In addition, we find that, when injected alone, Ro 15-1788 has no anxiogenic effects while beta-CCM has anxiogenic properties. We therefore propose that beta-CCM is an anxiogenic convulsant benzodiazepine antagonist and that Ro 15-1788 is a non-anxiogenic non-convulsant benzodiazepine antagonist.

Enhanced responsiveness of alpha-noradrenergic receptors following discrete electrolytic lesions of the nucleus locus coeruleus: a behavioral demonstration.

Locomotor activity was evaluated in groups of reserpine-treated mice administered the catecholamine receptor agonists apomorphine and clonidine. Pretreatment of selected groups of mice with discrete electrolytic destruction of the nucleus locus coeruleus (LC) resulted in a clonidine-potentiation of apomorphine-stimulated locomotor activity. This effect was greater in unilateral than bilateral lesioned mice. LC lesions also significantly reduced the level of locomotor habituation achieved within a 60 min observation period. The data are interpreted to suggest that discrete lesions of the nucleus LC results in increased alpha-noradrenergic receptor sensitivity.

An investigation of the clonality of human autoimmune thyroglobulin antibodies and their light chains.

Thyroglobulin antibodies in the sera from 31 patients with a variety of disorders were studied by isoelectric focusing. Only one gave a spectrotype indicative of a monoclonal response, the other 30 giving spectrotypes characteristic of polyclonal responses. There was evidence of clonal dominance in some of the sera and each gave a different spectrotype. Light chains were prepared from five thyroglobulin antibodies purified by affinity chromatography. There was no restriction in the spectrotypes when compared with light chains prepared from normal immunoglobulin.