Improved fertility following a gonadotropin-releasing hormone treatment on day 2 of an estradiol and progesterone-based timed-artificial insemination protocol in lactating dairy cows.

The present study evaluated the addition of gonadotropin-releasing hormone (GnRH) concomitant or 2 d after the beginning of protocols initiated with estradiol benzoate (EB). A total of 459 multiparous and 371 primiparous lactating Holstein cows were enrolled in the study. Weekly cohorts of cows were randomly assigned to 1 of 3 experimental groups that differed in the strategy to initiate the timed AI (TAI protocol. On d 0, all cows received a 1.55-g progesterone (P4) implant. Additionally, cows in the EBd0 group received 2 mg of EB i.m.; cows in the EBd0-GnRHd0 group were treated simultaneously on d 0 with 2 mg of EB plus 100 µg of gonadorelin diacetate tetrahydrate (GnRH) i.m.; and cows in the EBd0-GnRHd2 group received 2 mg of EB on d 0 and 100 µg of GnRH 48 h later (d 2). The remaining treatments in the protocol were similar among groups and included 0.53 mg (i.m.) of cloprostenol sodium (PGF2α) on d 7, followed by a second PGF2α treatment on d 9 (at the time of P4 implant withdrawal) and 1 mg of estradiol cypionate i.m. Then, TAI was performed on d 11 (48 h after P4 removal) in all experimental groups. We detected an effect of treatment on pregnancy per AI (P/AI) on d 30, in which cows from the EBd0-GnRHd2 group demonstrated greater fertility than EBd0 cows, whereas cows in the EBd0-GnRHd0 group did not differ among EBd0 and EBd0-GnRHd0 (40.5 vs. 30.4 vs. 34.4%, respectively). In summary, GnRH treatment at the beginning of an estradiol and P4-based TAI protocol increased fertility only when GnRH was given on d 2. Moreover, a more pronounced positive effect of this strategy was observed in particular classes of cows: multiparous cows, cows with greater milk production, and those receiving the first service.

Assessment of a trap based Aedes aegypti surveillance program using mathematical modeling.

The goal of this study was to assess the goodness-of-fit of theoretical models of population dynamics of Aedes aegypti to trap data collected by a long term entomological surveillance program. The carrying capacity K of this vector was estimated at city and neighborhood level. Adult mosquito abundance was measured via adults collected weekly by a network of sticky traps (Mosquitraps) from January 2008 to December 2011 in Vitória, Espírito Santo, Brazil. K was the only free parameter estimated by the model. At the city level, the model with temperature as a driver captured the seasonal pattern of mosquito abundance. At the local level, we observed a spatial heterogeneity in the estimated carrying capacity between neighborhoods, weakly associated with environmental variables related to poor infrastructure. Model goodness-of-fit was influenced by the number of sticky traps, and suggests a minimum of 16 traps at the neighborhood level for surveillance.

DengueME: A Tool for the Modeling and Simulation of Dengue Spatiotemporal Dynamics.

The prevention and control of dengue are great public health challenges for many countries, particularly since 2015, as other arboviruses have been observed to interact significantly with dengue virus. Different approaches and methodologies have been proposed and discussed by the research community. An important tool widely used is modeling and simulation, which help us to understand epidemic dynamics and create scenarios to support planning and decision making processes. With this aim, we proposed and developed DengueME, a collaborative open source platform to simulate dengue disease and its vector's dynamics. It supports compartmental and individual-based models, implemented over a GIS database, that represent Aedes aegypti population dynamics, human demography, human mobility, urban landscape and dengue transmission mediated by human and mosquito encounters. A user-friendly graphical interface was developed to facilitate model configuration and data input, and a library of models was developed to support teaching-learning activities. DengueME was applied in study cases and evaluated by specialists. Other improvements will be made in future work, to enhance its extensibility and usability.

Seasonal and nonseasonal dynamics of Aedes aegypti in Rio de Janeiro, Brazil: fitting mathematical models to trap data.

Mathematical models suggest that seasonal transmission and temporary cross-immunity between serotypes can determine the characteristic multi-year dynamics of dengue fever. Seasonal transmission is attributed to the effect of climate on mosquito abundance and within host virus dynamics. In this study, we validate a set of temperature and density dependent entomological models that are built-in components of most dengue models by fitting them to time series of ovitrap data from three distinct neighborhoods in Rio de Janeiro, Brazil. The results indicate that neighborhoods differ in the strength of the seasonal component and that commonly used models tend to assume more seasonal structure than found in data. Future dengue models should investigate the impact of heterogeneous levels of seasonality on dengue dynamics as it may affect virus maintenance from year to year, as well as the risk of disease outbreaks.

The exoribonuclease Dis3L2 defines a novel eukaryotic RNA degradation pathway.

The final step of cytoplasmic mRNA degradation proceeds in either a 5'-3' direction catalysed by Xrn1 or in a 3'-5' direction catalysed by the exosome. Dis3/Rrp44, an RNase II family protein, is the catalytic subunit of the exosome. In humans, there are three paralogues of this enzyme: DIS3, DIS3L, and DIS3L2. In this work, we identified a novel Schizosaccharomyces pombe exonuclease belonging to the conserved family of human DIS3L2 and plant SOV. Dis3L2 does not interact with the exosome components and localizes in the cytoplasm and in cytoplasmic foci, which are docked to P-bodies. Deletion of dis3l2(+) is synthetically lethal with xrn1Δ, while deletion of dis3l2(+) in an lsm1Δ background results in the accumulation of transcripts and slower mRNA degradation rates. Accumulated transcripts show enhanced uridylation and in vitro Dis3L2 displays a preference for uridylated substrates. Altogether, our results suggest that in S. pombe, and possibly in most other eukaryotes, Dis3L2 is an important factor in mRNA degradation. Therefore, this novel 3'-5' RNA decay pathway represents an alternative to degradation by Xrn1 and the exosome.

Telomeres avoid end detection by severing the checkpoint signal transduction pathway.

Telomeres protect the normal ends of chromosomes from being recognized as deleterious DNA double-strand breaks. Recent studies have uncovered an apparent paradox: although DNA repair is prevented, several proteins involved in DNA damage processing and checkpoint responses are recruited to telomeres in every cell cycle and are required for end protection. It is currently not understood how telomeres prevent DNA damage responses from causing permanent cell cycle arrest. Here we show that fission yeast (Schizosaccharomyces pombe) cells lacking Taz1, an orthologue of human TRF1 and TRF2 (ref. 2), recruit DNA repair proteins (Rad22(RAD52) and Rhp51(RAD51), where the superscript indicates the human orthologue) and checkpoint sensors (RPA, Rad9, Rad26(ATRIP) and Cut5/Rad4(TOPBP1)) to telomeres. Despite this, telomeres fail to accumulate the checkpoint mediator Crb2(53BP1) and, consequently, do not activate Chk1-dependent cell cycle arrest. Artificially recruiting Crb2(53BP1) to taz1Δ telomeres results in a full checkpoint response and cell cycle arrest. Stable association of Crb2(53BP1) to DNA double-strand breaks requires two independent histone modifications: H4 dimethylation at lysine 20 (H4K20me2) and H2A carboxy-terminal phosphorylation (γH2A). Whereas γH2A can be readily detected, telomeres lack H4K20me2, in contrast to internal chromosome locations. Blocking checkpoint signal transduction at telomeres requires Pot1 and Ccq1, and loss of either Pot1 or Ccq1 from telomeres leads to Crb2(53BP1) foci formation, Chk1 activation and cell cycle arrest. Thus, telomeres constitute a chromatin-privileged region of the chromosomes that lack essential epigenetic markers for DNA damage response amplification and cell cycle arrest. Because the protein kinases ATM and ATR must associate with telomeres in each S phase to recruit telomerase, exclusion of Crb2(53BP1) has a critical role in preventing telomeres from triggering cell cycle arrest.

Inactivation of cleavage factor I components Rna14p and Rna15p induces sequestration of small nucleolar ribonucleoproteins at discrete sites in the nucleus.

Small nucleolar RNAs (snoRNAs) associate with specific proteins forming small nucleolar ribonucleoprotein (snoRNP) particles, which are essential for ribosome biogenesis. The snoRNAs are transcribed, processed, and assembled in snoRNPs in the nucleoplasm. Mature particles are then transported to the nucleolus. In yeast, 3'-end maturation of snoRNAs involves the activity of Rnt1p endonuclease and cleavage factor IA (CFIA). We report that after inhibition of CFIA components Rna14p and Rna15p, the snoRNP proteins Nop1p, Nop58p, and Gar1p delocalize from the nucleolus and accumulate in discrete nucleoplasmic foci. The U14 snoRNA, but not U3 snoRNA, similarly redistributes from the nucleolus to the nucleoplasmic foci. Simultaneous depletion of either Rna14p or Rna15p and the nuclear exosome component Rrp6p induces accumulation of poly(A)(+) RNA at the snoRNP-containing foci. We propose that the foci detected after CFIA inactivation correspond to quality control centers in the nucleoplasm.

Depletion of the yeast nuclear exosome subunit Rrp6 results in accumulation of polyadenylated RNAs in a discrete domain within the nucleolus.

Recent data reveal that a substantial fraction of transcripts generated by RNA polymerases I, II, and III are rapidly degraded in the nucleus by the combined action of the exosome and a noncanonical poly(A) polymerase activity. This work identifies a domain within the yeast nucleolus that is enriched in polyadenylated RNAs in the absence of the nuclear exosome RNase Rrp6 or the exosome cofactor Mtr4. In normal yeast cells, poly(A)(+) RNA was undetectable in the nucleolus but the depletion of either Rrp6 or Mtr4 led to the accumulation of polyadenylated RNAs in a discrete subnucleolar region. This nucleolar poly(A) domain is enriched for the U14 snoRNA and the snoRNP protein Nop1 but is distinct from the nucleolar body that functions in snoRNA maturation. In strains lacking both Rrp6 and the poly(A) polymerase Trf4, the accumulation of poly(A)(+) RNA was suppressed, suggesting the involvement of the Trf4-Air1/2-Mtr4 polyadenylation (TRAMP) complex. The accumulation of polyadenylated snoRNAs in a discrete nucleolar domain may promote their recognition as substrates for the exosome.