Impaired Male Meiosis due to Irregular Synapsis Coupled with Cytomixis in a New Diploid Cytotype of Dianthus angulatus (Caryophyllaceae) from Indian Cold Deserts

Dianthus angulatus (Caryophyllaceae) is cytologically examined here for the first time for the area of India. The diploid chromosome count of 2n?=?30, ascertained here, represents a new cytotype, supplementing the earlier report of a hexaploid cytotype with 2n?=?90 from outside of India. We report here the occurrence of two plants showing impaired meiosis due to irregular synapsis and cytomixis collected from Kinnaur district, Himachal Pradesh (India). The other plants of this species collected in Lahaul-Spiti region showed normal male meiosis (n?=?15) with a high (95%?100%) pollen fertility and normal seed set, and they reproduce sexually. Irregular synapsis in two plants from the Kinnaur region is characterized by the complete absence of chromosome pairing and the presence of 30 univalents at diakinesis and meta-anaphase. In addition, other meiotic irregularities were found, such as unoriented chromosomes, laggards, precocious movements of univalents at anaphase-I and micronuclei at telophase. Microsporogenesis was also abnormal, resulting in the formation of monads, dyads, triads, polyads, and tetrads with micronuclei. The occurrence of intra- and intermicrosporal chromatin material transfer during microsporogenesis was observed, which is a rather rarely observed phenomenon. The synaptic irregularities coupled with chromatin transfer in these plants seem to be responsible for the high pollen sterility (38%?42%) and heterogeneously sized pollen grains. In these plants no seeds were set, and plants reproduced vegetatively through root suckers.     

Prokaryotic gene finding based on physicochemical characteristics of codons calculated from molecular dynamics simulations

An ab initio model for gene prediction in prokaryotic genomes is proposed based on physicochemical characteristics of codons calculated from molecular dynamics (MD) simulations. The model requires a specification of three calculated quantities for each codon: the double-helical trinucleotide base pairing energy, the base pair stacking energy, and an index of the propensity of a codon for protein-nucleic acid interactions. The base pairing and stacking energies for each codon are obtained from recently reported MD simulations on all unique tetranucleotide steps, and the third parameter is assigned based on the conjugate rule previously proposed to account for the wobble hypothesis with respect to degeneracies in the genetic code. The third interaction propensity parameter values correlate well with ab initio MD calculated solvation energies and flexibility of codon sequences as well as codon usage in genes and amino acid composition frequencies in ∼175,000 protein sequences in the Swissprot database. Assignment of these three parameters for each codon enables the calculation of the magnitude and orientation of a cumulative three-dimensional vector for a DNA sequence of any length in each of the six genomic reading frames. Analysis of 372 genomes comprising ∼350,000 genes shows that the orientations of the gene and nongene vectors are well differentiated and make a clear distinction feasible between genic and nongenic sequences at a level equivalent to or better than currently available knowledge-based models trained on the basis of empirical data, presenting a strong support for the possibility of a unique and useful physicochemical characterization of DNA sequences from codons to genomes.     

Use of metabolic stimulators and inhibitors for enhanced production of beta-carotene and lycopene by Blakeslea trispora NRRL 2895 and 2896

This work investigates the potential of metabolic stimulators, firstly to enhance the production of beta-carotene, and later use of inhibitors of lycopene cyclase so as to accumulate lycopene in the fermentation medium. Various non-ionic surfactants, natural oils, stimulators such as amino-acids, tricarboxylic acid cycle (TCA) intermediates, vitamin A and antibiotics were investigated for improved production of beta-carotene using the zygomycete fungus Blakeslea trispora. Span 20 at 0.2% increased the beta-carotene production from 139 mg/l to 318 mg/l. Examination of the mycelial morphology of the B. trispora with span 20 showed a shorter mycelial length, which allowed a well-dispersed growth of B. trispora. Supplementation of the medium with 1000 ppm vitamin A acetate gave highest concentration of beta-carotene (830+/-6 mg/l). Several chemical inhibitors such as imidazole, pyridine, triethylamine, piperidine, and nicotinic acid were then evaluated to block the biosynthesis at lycopene. Piperidine at 500 ppm gave a 7.76-fold improvement, and produced high titers of lycopene (775+/-5 mg/l) in a medium supplemented with vitamin A acetate.     

The influence of p,p'-DDT, alpha-chlordane, heptachlor and endrin on hepatic and renal carbohydrate metabolism and cyclic AMP-adenyl cyclase system

Administration of an acute oral dose of p,p′-DDT (600 mg/kg), α-chlordane (200 mg/kg), heptachlor (200 mg/kg) and endrin (50 mg/kg) produced a significant rise in the concentration of serum glucose and urea and a lowering of hepatic glycogen. In addition, treatment with either of these insecticides significantly increased the activities of hepatic and renal pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase, the four enzymes which play a key, rate-limiting role in the process of gluconeogenesis. Treatment with p,p′-DDT, α-chlordane, heptachlor or endrin proved equally effective in elevating the levels of endogenous cyclic AMP and augmenting the activity of basal- and fluoride-stimulated forms of adenyl cyclase in both tissues. Whereas renal phosphodiesterase was decreased slightly by p,p′-DDT, the activity of this cyclic AMP-degrading enzyme remained unaltered following the administration of other pesticides. Our data indicate that the pesticide-induced alterations in carbohydrate metabolism of liver and kidney may be associated with an enhanced ability of these organs to synthesize cyclic AMP.     

Optimisation of conditions of synthesis of oxidised starch from corn and amaranth for use in film-forming applications

Gum arabic is used as an encapsulating agent because of its film-forming ability. However, India has to import gum arabic for its domestic requirement. Oxidised starch has been reported as a substitute for gum arabic but no data are reported on the exact conditions of oxidation of starch or the analytical indicators for determining the suitability of the product for such a purpose. This work reports on the effect of process conditions for oxidation of corn and waxy amaranth starch with film-forming ability as the major criterion. The process was followed using the analytical indicators of oxidation such as carboxyl content, chlorine consumption and ferricyanide number.     

METABOLIC CONTROL MECHANISMS IN MAMMALIAN SYSTEMS

Abstract— The regulation by thyroid hormone of the activities of hexokinase (ATP: D-hexose 6-phosphotransferase; EC 2.7.1.1), phosphofructokinase (ATP: D-fructose-6- phosphate 1-phosphotransferase; EC 2.7.1.11) and pyruvate kinase (ATP: pyruvate phosphotransferase; EC 2.7.1.40) has been investigated in the soluble fractions of the cerebral cortex and cerebellum of the rat. Ontogenetic studies on these key glycolytic enzymes demonstrated marked increases in the normal cerebral cortex between 1 day and 1 yr of age; less pronounced increases in enzyme activities were noted in the normal cerebellum. Neonatal thyroidectomy, induced by treatment of 1-day-old rats with 100 μCi of ¹³¹I, ied to an impairment of body and brain growth and inhibited the developmental increases in hexokinase, phosphofructokinase and pyruvate kinase in both the cerebral cortex and cerebellum. Whereas 50 μCi of ¹³¹I had little or no effect on these brain enzymes, 200 μCi of the radioisotope markedly inhibited (35–65 per cent) the developmental increases of the various enzyme activities investigated. When administration of the radioisotope was delayed for 20 days after birth, little or no inhibition of the development of brain glycolytic enzymes was observed. Whereas treatment of normal neonatal animals with L-tri-iodothyronine had no significant effect on the activities of cerebro-cortical and cerebellar glycolytic enzymes, the hormone increased their activities in young cretinous rats. However, when the initiation of tri-iodothyronine treatment was delayed until neonatally thyroidectomized rats had reached adulthood, this hormone failed to produce any appreciable change in enzyme activity. Our results indicate that thyroid hormone exerts an important regulatory influence on the activities of hexokinase, phosphofructokinase and pyruvate kinase in the developing cerebral cortex and cerebellum.