Structure of RNA in ribosomes

The 50S and 30S ribosomes and 23S and 16S RNA were hydrolyzed with ribonuclease A. The rate constants and number of fragments produced were determined for each reaction. The conformation of 23S RNA changes when the RNA is extracted from the ribosome. Specific regions of the RNA in 50S and 30S ribosomes are protected from hydrolysis by the ribosomal proteins.     

Pituitary gastrins occur in corticotrophs and melanotrophs

The gut hormone gastrin was identified in pituitary cells containing adrenocorticotropic hormone and alpha-melanocyte--stimulating hormone by region-specific immunocytochemistry and radioimmunoassay. Smaller amounts of gastrin were found in nerve fibers of the neural lobe and pituitary stalk. Since adrenocorticotropic hormone--like peptides occur in antropyloric gastrin cells, these data indicate a considerable similarity in peptide composition of pituitary and gastrointestinal endocrine cells and reinforces questions of multiple hormone production.     

Anopheles hackeri,a vector of Plasmodium knowlesi in Malaya

Anopheles hackeri, a mosquito commonly found breeding in nipa palm leaf bases along the Malayan coast, was demonstrated to be infected with Plasmodium knowlesi by the inoculation of sporozoites into an uninfected rhesus monkey. This was the first demonstration of a natural vector of any monkey malaria.     

Heterogeneity of 5S RNA in fungal ribosomes

Neurospora crassa has at least seven types of 5S RNA genes (alpha, beta, gamma, epsilon, delta, zeta, and eta) with different coding regions. A high resolution gel electrophoresis system was developed to separate minor 5S RNA's from the major 5S RNA (alpha). A study of several Neurospora crassa strains, four other species in the genus Neurospora, members of two closely related genera, and three distantly related genera demonstrated that 5S RNA heterogeneity is common among fungi. In addition, different 5S RNA's are present in Neurospora ribosomes. The finding that fungal ribosomes are structurally heterogeneous suggests that ribosomes may be functionally heterogeneous as well.     

Parthenogenesis: does it occur spontaneously in mice?

If parthenogenesis occurred in bisexual organisms, it would produce an excess of females and depress the sex ratio. The phenotypes of female mice, from matings that produce an excess of females, were examined for evidence of the presence of marker genes of paternal origin. All proved to be hybrids of the maternal and paternal strains, thus excluding parthenogenesis as the cause of the low sex ratio.     

Estradiol fatty acid esters occur naturally in human blood

Treatment of nonpolar ether extracts of human female blood with mild alkali produced more immunoassayable estradiol than the unhydrolyzed extract. Analysis of the serum extracts showed that the substance which released immunoreactive estradiol after hydrolysis has chromatographic properties identical to those of fatty acid esters of estradiol esterified at carbon 17. The physiological role of these previously unknown endogenous esters might be inferred from their structural similarity to synthetic drugs used therapeutically for their prolonged estrogenic action.     

Mendelian and uniparental alterations in erythromycin binding by plastid ribosomes

Erythromycin binds specifically to the 52S subunit of the chloroplast ribosome of Chlamydomonas reinhardi. A number of erythromycin-resistant mutants whose ribosomes have lost their affinity for the antibiotic have been isolated, but the sedimentation properties of their ribosomes are indistinguishable from those of the wild-type strain. These mutants represent at least three genetic loci. Two of them show Mendelian inheritance, and one of them is inherited in a uniparental manner.     

Decapping and decay of messenger RNA occur in cytoplasmic processing bodies

A major pathway of eukaryotic messenger RNA (mRNA) turnover begins with deadenylation, followed by decapping and 5' to 3' exonucleolytic decay. We provide evidence that mRNA decapping and 5' to 3' degradation occur in discrete cytoplasmic foci in yeast, which we call processing bodies (P bodies). First, proteins that activate or catalyze decapping are concentrated in P bodies. Second, inhibiting mRNA turnover before decapping leads to loss of P bodies; however, inhibiting turnover at, or after, decapping, increases the abundance and size of P bodies. Finally, mRNA degradation intermediates are localized to P bodies. These results define the flux of mRNAs between polysomes and P bodies as a critical aspect of cytoplasmic mRNA metabolism and a possible site for regulation of mRNA degradation.     

Sleep disorders: disorders of arousal? Enuresis, somnambulism, and nightmares occur in confusional states of arousal, not in "dreaming sleep"

In summary, the classical sleep disorders of nocturnal enuresis, somnambulism, the nightmare, and the sleep terror occur preferentially during arousal from slow-wave sleep and are virtually never associated with the rapid-eye-movement dreaming state. Original data are reported here which indicate that physiological differences from normal subjects, of a type predisposing the individual to a particular attack pattern, are present throughout the night. The episode, at least in the case of enuresis, appears to be simply a reinforcement of these differences to a clinically overt level. A number of features are common to all four sleep disorders. These had been shown previously to be attributable to the arousal itself. New data obtained by means of evoked potential techniques suggest that these common symptoms of the confusional period that follows non-REM sleep are related to alterations of cerebral reactivity, at least of the visual system. The symptoms which distinguish the individual attack types (that is, micturition, prolonged confusional fugues, overt terror) appear to be based upon physiological changes present throughout sleep which are markedly accentuated during arousal from slow-wave sleep. These changes may in some way be related to diurnal psychic conflicts. But, to date, it has proved impossible to demonstrate potentially causal psychological activity, dreaming or other forms of mental activity, or even a psychological void in sleep just preceding the attacks. The presence of all-night or even daytime predisposing physiological changes and the difficulty in obtaining any solid evidence of a preceding psychological cause explain, no doubt, why the results of efforts to cure the disorders at the moment of their occurrence (for example, by conditioning procedures in nocturnal enuresis) have been far from satisfactory. I stress the points that the attacks are best considered disorders of arousal and that the slow-wave sleep arousal episode which sets the stage for these attacks is a normal cyclic event. Indeed it is the most intense recurrent arousal that an individual regularly experiences. The most fruitful possibilities for future research would appear to be more detailed studies of those physiological changes that predispose individuals to certain types of attacks when they undergo intense arousal or stress; the reversal of these changes by psychological or pharmacological means; and more refined investigations of the physiological and psychological characteristics of the process of cyclic arousal from non-REM sleep.     

Carbon tetrachloride poisoning in rats: alteration in ribosomes of the liver

Microsomes from livers of albino rats treated with carbon tetrachloride were compared with those from normal rats with respect to their ability to incorporate amino acid. Acute carbon tetrachloride poisoning results in depressed capacity of microsomes to incorporate amino acid. From ultracentrifugal data, there is an apparent dissociation of 79S ribosomes into 54S components.     

广州地区桔小实蝇的发生与综合防治关键措施

桔小实蝇(Bactrocera dorsalis)是危害水果和蔬菜的危险性有害生物。介绍了桔小实蝇在广州地区的发生特点、生活史及生活习性,对该虫采取诱杀成虫、套袋及收集和处理虫果、释放不育蝇、化学防治和行政管理等综合关键措施,可提高对桔小实蝇的防治效果。     

Excess polymorphisms in genes for membrane proteins in Plasmodium falciparum

The detection of single-nucleotide polymorphisms in pathogenic microorganisms has normally been carried out by trial and error. Here we show that DNA hybridization with high-density oligonucleotide arrays provides rapid and convenient detection of single-nucleotide polymorphisms in Plasmodium falciparum, despite its exceptionally high adenine-thymine (AT) content (82%). A disproportionate number of polymorphisms are found in genes encoding proteins associated with the cell membrane. These genes are targets for only 22% of the oligonucleotide probes but account for 69% of the polymorphisms. Genetic variation is also enriched in subtelomeric regions, which account for 22% of the chromosome but 76% of the polymorphisms.