Dicer structure and function: conserved and evolving features.

RNase III Dicer produces small RNAs guiding sequence-specific regulations, with important biological roles in eukaryotes. Major Dicer-dependent mechanisms are RNA interference (RNAi) and microRNA (miRNA) pathways, which employ distinct types of small RNAs. Small interfering RNAs (siRNAs) for RNAi are produced by Dicer from long double-stranded RNA (dsRNA) as a pool of different small RNAs. In contrast, miRNAs have specific sequences because they are precisely cleaved out from small hairpin precursors. Some Dicer homologs efficiently generate both, siRNAs and miRNAs, while others are adapted for biogenesis of one small RNA type. Here, we review the wealth of recent structural analyses of animal and plant Dicers, which have revealed how different domains and their adaptations contribute to substrate recognition and cleavage in different organisms and pathways. These data imply that siRNA generation was Dicer's ancestral role and that miRNA biogenesis relies on derived features. While the key element of functional divergence is a RIG-I-like helicase domain, Dicer-mediated small RNA biogenesis also documents the impressive functional versatility of the dsRNA-binding domain.

Does being stricter mean doing better? Different effects of environmental policy stringency on quality of life, green innovation, and international cooperation.

Nowadays, when we are facing several strict regulations, the question arises - does higher strictness lead to the desired results? This study addresses the fact that less research attention has focused on the effects of environmental policy stringency (EPS) on perceived health expressing quality of life, and on green international cooperation. In addition, previous research has provided rather mixed results on the impact of EPS on green innovation. Therefore, we fill an interesting research gap and help better understand the relationship between market-based and non-market-based EPS, perceived health, green innovations, and green international cooperation in OECD (Organization for Economic Co-operation and Development) countries. Using three complementary databases provided by OECD, Eurostat, and the World Bank and the classical linear regression model, we confirm hypotheses that strong market-based EPS and green international cooperation have positive effects on perceived health. Surprisingly, contrary to the findings of prior research, we do not confirm the positive effects of market-based and non-market-based EPS on green international cooperation. This study contributes to the literature on the Porter hypothesis, technological collaborations in green technological development, and environmental innovation theory. In addition, this study provides several practical implications for policymakers across OECD countries.

Structural and functional basis of mammalian microRNA biogenesis by Dicer.

MicroRNA (miRNA) and RNA interference (RNAi) pathways rely on small RNAs produced by Dicer endonucleases. Mammalian Dicer primarily supports the essential gene-regulating miRNA pathway, but how it is specifically adapted to miRNA biogenesis is unknown. We show that the adaptation entails a unique structural role of Dicer's DExD/H helicase domain. Although mice tolerate loss of its putative ATPase function, the complete absence of the domain is lethal because it assures high-fidelity miRNA biogenesis. Structures of murine Dicer•-miRNA precursor complexes revealed that the DExD/H domain has a helicase-unrelated structural function. It locks Dicer in a closed state, which facilitates miRNA precursor selection. Transition to a cleavage-competent open state is stimulated by Dicer-binding protein TARBP2. Absence of the DExD/H domain or its mutations unlocks the closed state, reduces substrate selectivity, and activates RNAi. Thus, the DExD/H domain structurally contributes to mammalian miRNA biogenesis and underlies mechanistical partitioning of miRNA and RNAi pathways.

Proximate Chemical Composition, Amino Acids Profile and Minerals Content of Meat Depending on Carcass Part, Sire Genotype and Sex of Meat Rabbits.

The aim of the study was to assess the effects of the sire genotype, sex and carcass part on the composition of the meat of rabbits, which were fattened under conditions where no synthetic drugs were used. As for carcass parts, the higher content of both total amino acids (AA) and all essential AA (EAA) monitored was found in the Longissimus thoracis et lumborum (LTL) muscle as compared to hind leg meat (p ˂ 0.001). Significant effects of the rabbit sire genotype and the genotype x sex interaction on proportions of some AA in meat were found (p ˂ 0.001). Crossbreeding of the Mecklenburger Schecke (MS) sires with a commercial dam line of HYLA rabbits resulted in a lower proportion of the total AA and all EAA monitored in meats of MS sired males as compared to MS sired females and HYLA rabbits (p ˂ 0.05). The sex-related effect on AA profile was not so noticeable in final commercial crossbreds of HYLA rabbits when compared to MS sired progeny. These findings point to a possible risk of alterations in the nutritional quality of meat proteins when using different rabbit sire genotypes than those originally intended for the specific commercial crossbreeding scheme. However, on the contrary, higher contents of magnesium (p ˂ 0.05), manganese (p ˂ 0.001) and zinc (p ˂ 0.05) were found in meats of MS sired progeny as compared to HYLA rabbits.

Cooperation between intrinsically disordered and ordered regions of Spt6 regulates nucleosome and Pol II CTD binding, and nucleosome assembly.

Transcription elongation factor Spt6 associates with RNA polymerase II (Pol II) and acts as a histone chaperone, which promotes the reassembly of nucleosomes following the passage of Pol II. The precise mechanism of nucleosome reassembly mediated by Spt6 remains unclear. In this study, we used a hybrid approach combining cryo-electron microscopy and small-angle X-ray scattering to visualize the architecture of Spt6 from Saccharomyces cerevisiae. The reconstructed overall architecture of Spt6 reveals not only the core of Spt6, but also its flexible N- and C-termini, which are critical for Spt6's function. We found that the acidic N-terminal region of Spt6 prevents the binding of Spt6 not only to the Pol II CTD and Pol II CTD-linker, but also to pre-formed intact nucleosomes and nucleosomal DNA. The N-terminal region of Spt6 self-associates with the tSH2 domain and the core of Spt6 and thus controls binding to Pol II and nucleosomes. Furthermore, we found that Spt6 promotes the assembly of nucleosomes in vitro. These data indicate that the cooperation between the intrinsically disordered and structured regions of Spt6 regulates nucleosome and Pol II CTD binding, and also nucleosome assembly.

Chemical and physical characteristics of lamb meat related to crossbreeding of Romanov ewes with Suffolk and Charollais sires.

The aim was to evaluate the effects of crossbreeding Romanov (RO) ewes with Suffolk (SF) and Charollais (CH) sires on the chemicophysical characteristics and FA profile of the Quadriceps femoris muscle (QFM) in lambs fattened under organic conditions. The experimental animals were male lamb twins of two different crossbreds; CH 50 RO 50 and SF 50 RO 50. Lambs were slaughtered at an average live weight of 31kg. CH 50 RO 50 displayed higher contents of dry matter and intramuscular fat of the QFM. A lower pH value of CH 50 RO 50 was reflected in an increase of WHC. Meat of SF 50 RO 50 lambs had more lightness (L*) and yellowness (b*). The CH 50 RO 50 genotype showed a significantly higher proportion of C18:3n-3cis and n-3 PUFA than the SF 50 RO 50 genotype. The genotype also affected the Δ(9)-desaturase (16) index.

Impact of housing technology on blood plasma corticosterone levels in laying hens.

The aim of the present study was to test the hypothesis that keeping laying hens in an enriched environment supposed to represent a better welfare for the birds is accompanied by decreased corticosterone levels, compared to hens kept under traditional conditions. Plasma corticosterone levels in hens reared in standard and enriched cages and those kept on deep litter from 15 to 75 weeks of age were evaluated. The highest corticosterone levels were observed in hens kept on deep litter, which was associated with a lower intensity of egg production, longest time of movement and a high percentage of time spent dustbathing and scratching. Hens housed in the enriched environment exhibited low levels of aggression, low body weight at the end of the experiment and similar or higher corticosterone levels compared to those of hens kept under standard conditions. Thus, the results of the present study show that housing technologies which are more similar to the animal's natural environment need not be associated with decreased levels of plasma corticosterone. Keeping hens in traditional cage technology was not found to be particularly stressful, which may be an important finding with respect to the current restrictions on outside housing in regions with an increased risk of viral infection.