Search

microRNA (miRNA)-mediated gene silencing is enacted through the recruitment of effector proteins that direct translational repression or degradation of mRNA targets, but the relative importance of their activities for animal development remains unknown. Our concerted proteomic surveys identified the uncharacterized GYF-domain encoding protein GYF-1 and its direct interaction with IFE-4, the ortholog of the mammalian translation repressor 4EHP, as key miRNA effector proteins in Caenorhabditis elegans. Recruitment of GYF-1 protein to mRNA reporters in vitro or in vivo leads to potent translation repression without affecting the poly(A) tail or impinging on mRNA stability. Loss of gyf-1 is synthetic lethal with hypomorphic alleles of embryonic miR-35-42 and larval (L4) let-7 miRNAs, which is phenocopied through engineered mutations in gyf-1 that abolish interaction with IFE-4. GYF-1/4EHP function is cascade-specific, as loss of gyf-1 had no noticeable impact on the functions of other miRNAs, including lin-4 and lsy-6. Overall, our findings reveal the first direct effector of miRNA-mediated translational repression in C. elegans and its physiological importance for the function of several, but likely not all miRNAs., (© The Author(s) 2021. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Background: The Deadly Trio programme offered cardiovascular health checks to men over 40 in inner-city Birmingham. The aim was to increase diagnosis of diabetes, cardiovascular and kidney disease among this deprived and ethnically diverse population. Either patients' own general practitioners (GPs) were paid to provide health checks or patients were invited to an alternative provider., Methods: Routine data were sought from 68 participating practices. Logistic regression analysis was undertaken to determine the patient and practice factors associated with being screened and with being added to a disease register., Results: Data were obtained from 58 practices; 5871 (24.3%) of 24 166 eligible men were screened. Screening uptake was higher in those with a recorded phone number, South Asians and Blacks but lower in smokers. Compared to the alternative provider, uptake was higher among men registered with single-handed (but not multi-partner) GPs paid to provide health checks. South Asian, older and screened men were more often added to disease registers. Men with missing information and GP-screened men were less likely to be added to registers., Conclusions: The programme achieved higher screening uptake and diagnosis of disease among minority ethnic men. Single-handed GPs paid to provide screening (and their patients) were more responsive than multi-partner practices.

An aggressive, non-native haplotype (distinct genetic lineage within a species) of Phragmites australis is invading brackish and freshwater systems in the eastern United States, potentially displacing native haplotypes. We studied the differential susceptibility of native and non-native populations collected from sites throughout North America to the non-native aphid, Hyalopterus pruni. In a greenhouse study, we found significantly higher aphid populations on native haplotypes than on the non-native haplotype 2 mo after infestation. Aphid feeding caused chlorosis and death of native stems, and in some cases, killed whole native genets. The non-native plants remained relatively undamaged. In a field study, non-native plants had significantly lower aphid densities than native plants or remained aphid free. There was an interactive effect in which aphid populations increased on the native plants over the 1-mo study period but remained low on non-native plants over the same period. The susceptibility of native North American populations of P. australis to non-native aphid infestation may indirectly affect the ability of these native plants to compete with non-native plant populations, ultimately contributing to the decline of native haplotypes.

In most eukaryotic cells, microtubules (MTs) are assembled at identified nucleating sites, such as centrosomes or spindle pole bodies. Higher plant cells do not possess such centrosome-like structures. Thus, the fundamental issues of where and how the intracellular plant MTs are nucleated remain highly debatable. A large body of evidence indicates that plant MTs emerge from the nuclear periphery. In this study, we developed an in vitro assay in which isolated maize nuclei nucleate MT assembly at a tubulin concentration (14 [mu]M of neurotubulin) that is not efficient for spontaneous MT assembly. No MT-stabilizing agents, such as taxol or dimethyl sulfoxide, were used. Our model provides evidence that the nuclear surface functions as a MT-nucleating site in higher plant cells. A monoclonal antibody raised against a pericentriolar antigen immunostained the surface of isolated nuclei, and a 100-kD polypeptide in 4 M urea-treated nuclear extracts was detected.

Endosperm mitotic cells microinjected with fluorescent phalloidin enabled us to follow the in vivo dynamics of the F-actin cytoskeleton. The fluorescent probe immediately bound to plant microfilaments. First, we investigated the active rearrangement of F-actin during chromosome migration, which appeared to be slowed down in the presence of phalloidin. These findings were compared with the actin patterns observed in mitotic cells fixed at different stages. Our second aim was to determine the origin of the actin filaments that appear at the equator during anaphase-telophase transition. It is not clear whether this F-actin is newly assembled at the end of mitosis and could control plant cytokinesis or whether it corresponds to a passive redistribution of broken polymers in response to microtubule dynamics. We microinjected the same cells twice, first in metaphase with rhodamine-phalloidin and then in late anaphase with fluorescein isothiocyanate-phalloidin. This technique enabled us to visualize two F-actin populations that are not co-localized, suggesting that actin is newly assembled during cell plate development. These in vivo data shed new light on the role of actin in plant mitosis and cytokinesis.

The pharmacokinetics of temocillin was studied in 16 subjects with varying degrees of renal functional impairment. The subjects were divided into three groups, depending on their creatinine clearance: Group A greater than 70 ml/min/1.73 m2; Group B 20-70ml/min/1.73 m2 and Group C less than 20 ml/min/1.72 m2. Following intravenous administration the total serum clearance of temocillin was reduced in patients with renal insufficiency. The distribution of temocillin into the tissues was not affected by renal dysfunction, apparent distribution volumes being 15.11, 16.01 and 13.81 in Groups A, B and C respectively. The change in clearance was reflected in an increased area under the serum concentration versus time curve from 418 mg h/l in Group A to 1301 mg h/l and 1553 mg h/l in Groups B and C respectively. The beta elimination half-life was also prolonged from 3.5 h in Group A 12.7 h in Group B and 17.5 h in Group C. The urinary excretion of temocillin was both delayed and reduced according to the extent of kidney damage. The reduction in temocillin clearance was proportional to the extent of reduction from normal of the clearance of creatinine. This relationship has been used to suggest dosage schedules for temocillin in patients with renal insufficiency.