Small nucleolar RNAs

Small nucleolar RNAs (snoRNAs) are an abundant class of non-protein-coding RNAs. In association with proteins they perform two most frequent nucleotide modifications in rRNAs and some other cellular RNAs: 2'-O-ribose methylation and pseudouridylation. SnoRNAs also participate in pre-rRNA cleavage and telomerase functions. Most snoRNAs fall into two families, box C/D and H/ACA, distinguished by the presence of conserved sequence boxes. Although C/D and H/ACA snoRNP proteins contain homologous regions, the assembly of these RNPs significantly differ. In addition, snoRNAs include the RNA component of RNAses P and MRP. The structure and function of small RNPs from Cajal bodies (small organelles associated with nucleoli) similar to snoRNP are also discussed.     

Small nucleolar RNA genes

Small nucleolar RNAs (snoRNAs) are one of the most numerous and well-studied groups of non-protein-coding RNAs. In complex with proteins, snoRNAs perform the two most common nucleotide modifications in rRNA: 2′-OH-methylation of ribose and pseudouridylation. Although the modification mechanisms and snoRNP structures are highly conserved, the snoRNA genes are surprisingly diverse in organization. In addition to genes transcribed independently, there are genes that are in introns of other genes, form clusters transcribed from a common promoter, or clusters in introns. Interestingly, one type of gene organization usually prevails in different taxa. Vertebrate snoRNAs mostly originate from introns of protein-coding genes; a small group of snoRNAs are encoded by introns of genes for noncoding RNAs.     

Chronic stress and its effects on adrenal cortex apoptosis in pregnant rats

The model of chronic intermittent stress by immobilization during pregnancy may produce alterations in the mechanisms that maintain adrenal gland homeostasis. In earlier investigations using this model, significant variations in plasma prolactin and corticosterone levels, and adrenal gland weights were observed. We hypothesized that chronic stress causes changes in apoptosis in the adrenal glands of pregnant rats. We identified and quantified apoptotic cells in the adrenal cortex and examined their ultrastructural characteristics using transmission electron microscopy. Adrenal glands of pregnant rats at gestation days 12, 17 and 21 were studied for control and experimental (stressed) rats. Immunolabelling techniques, stereological analysis and image quantification of adrenal gland sections were combined to determine differences in apoptosis in the different cell populations of the adrenal cortex. The apoptotic index of the experimental rats showed a significant reduction at gestation day 17, while at days 12 and 21 there were no differences from controls. Moreover, the apoptotic index of the reticular zones in control and experimental animals showed a significant increase compared to the glomerular and fascicular zones at the three gestation times studied. Chronic stress by immobilization reduced the caspase-dependent apoptotic index at gestation day 17, which may be related to variations in plasma concentrations of estrogens and prolactin.     

Effects of Piper hispidinervum on spermatogenesis and histochemistry of ovarioles of Spodoptera frugiperda

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), not only damages crops, but controlling its population also requires synthetic insecticides, which leads to selection of resistant populations and environmental contamination. Essential oils are an alternative for controlling this insect. There are few studies of the effects of these oils on the insect's reproductive system. We evaluated the effects of the long pepper, Piper hispidinervum, essential oil on the gonads of the armyworm and tested its possible influence on the fertility of this insect. Dosages of 30 and 50 mg/ml were tested in 3^rd instar caterpillars using the leaf immersion method. Testes and ovarioles were collected, fixed with 10% formalin and embedded in Historesin. The sections were stained with toluidine blue and Mallory trichrome to detect connective tissue, periodic acid-Schiff to detect neutral carbohydrates, and bromophenol blue to detect proteins. We found that the long pepper essential oil affected negatively the spermatogenesis and altered the histochemistry of the ovarioles of S. frugiperda. The effects of long pepper oil suggest that it is a promising tool for controlling the armyworm pest.     

Papilin, a novel component of basement membranes, in relation to ADAMTS metalloproteases and ECM development

Papilins are homologous, secreted extracellular matrix proteins which share a common order of protein domains. They occur widely, from nematodes to man, and can differ in the number of repeats of a given type of domain. Within one species the number of repeats can vary by differential RNA splicing. A distinctly conserved cassette of domains at the amino-end of papilins is homologous with a cassette of protein domains at the carboxyl-end of the ADAMTS subgroup of secreted, matrix-associated metalloproteases. Papilins primarily occur in basement membranes. Papilins interact with several extracellular matrix components and ADAMTS enzymes. Papilins are essential for embryonic development of Drosophila melanogaster and Caenorhabditis elegans.     

Comparison of Worm Control Strategies in Grazing Sheep in Denmark

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.