Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Follicle Deviation and Intrafollicular and Systemic Estradiol Concentrations in Mares

Abstract: By definition, follicle deviation begins on the day the two largest follicles of a wave begin to differ in growth rates. The relationships between follicle deviation and intrafollicular and systemic estradiol concentrations were studied in ponies, using a two-follicle model in which all but the two largest follicles were ablated. A 20-microliter sample of follicular fluid was obtained from each of the two follicles by transvaginal ultrasonography. In experiment 1, the two follicles were sampled when the larger follicle reached 15 mm. No differences (p > 0.05) in post-sampling follicle characteristics were found between control (n = 6) and sampled (n = 8) groups except that the growth rate was slower (p < 0.01) in the larger follicle between the day of sampling and the next day (0.7 +/- 0.7 mm per day) than in the controls (3.3 +/- 0.3 mm per day). The growth rates between 2 and 5 days after sampling were not different between groups. Follicular fluid estradiol-17beta concentrations were higher (p < 0.007) in the larger follicle (460 +/- 67 ng/ml; diameter, 16.4 +/- 0.4 mm) than in the smaller follicle (322 +/- 50 ng/ml; diameter, 14.6 +/- 0.6 mm). In experiment 2, the pair of follicles was sampled when the larger follicle reached 15 mm, 20 mm, or 25 mm (n = 5 per group). There were no significant differences among the three groups for day of deviation and diameters of larger and smaller follicles at deviation. The difference in diameter between the larger and smaller follicles was similar for the 15-mm (2.2 +/- 0.9 mm) and 20-mm (3.1 +/- 1.0 mm) groups, but the difference between follicles for the 25-mm group (7.9 +/- 1.2 mm) was greater (p < 0.004) than for the other two groups. In contrast, the differences in estradiol concentrations between the larger and smaller follicles increased (p < 0.0001) progressively for the 15-mm (13.0 +/- 86.8 ng/ml), 20-mm (722.0 +/- 173.8 ng/ml), and 25-mm (1873.5 +/- 310.3 ng/ml) groups. The first significant (p < 0.007) increase in systemic estradiol occurred between the day before and the day of the beginning of deviation. Detection of an increased difference in estradiol concentrations between the two follicles before the detection of a change in differences in diameter suggests, on a temporal basis, that estradiol is a candidate for involvement in the mechanism that leads to follicle-diameter deviation in mares.

Role of Luteinizing Hormone in Follicle Deviation Based on Manipulating Progesterone Concentrations in Mares

Abstract: The effects of several doses of progesterone on FSH and LH concentrations were used to study the role of the gonadotropins on deviation in growth rates of the two largest follicles during the establishment of follicle dominance. Progesterone was given to pony mares at a daily dose rate of 0 mg (controls), 30 mg (low dose), 100 mg (intermediate dose), and 300 mg (high dose). All follicles > or = 6 mm were ablated at Day 10 (Day 0 = ovulation) to initiate a new follicular wave; prostaglandin F(2alpha) was given to induce luteolysis, and progesterone was given from Days 10 to 24. The low dose did not significantly alter any of the ovarian or gonadotropin end points. The high dose reduced (P < 0.05) the ablation-induced FSH concentrations on Day 11. Maximum diameter of the largest follicle (17.2 +/- 0.6 mm) and the second-largest follicle (15.5 +/- 0.9 mm) in the high-dose group was less (P < 0.04) than the diameter of the second-largest follicle in the controls (20.0 +/- 1.0 mm) at the beginning of deviation (Day 16.7 +/- 0.4). Thus, the growth of the two largest follicles was reduced by the high dose, presumably through depression of FSH, so that the follicles did not attain a diameter characteristic of deviation in the controls. The intermediate dose did not affect FSH concentrations. However, the LH concentrations increased in the control, low, and intermediate groups, but then decreased (P < 0.05) in the intermediate group to pretreatment levels. The LH decrease in the intermediate group occurred 2 days before deviation in the controls. The maximum diameter of the largest follicle was less (P < 0.0001) in the intermediate group (27.3 +/- 1.8 mm) than in the controls (38.9 +/- 1.5 mm), but the maximum diameter of the second-largest follicle was not different between the two groups (19.0 +/- 1.1 vs. 20.3 +/- 1.0 mm). Thus, the onset of deviation, as assessed by the second-largest follicle, was not delayed by the decrease in LH. Diameter of the largest follicle by Day 18 in the intermediate group (23.1 +/- 1.6 mm) was less (P < 0.05) than in the controls (28.0 +/- 1.0 mm). These results suggest that circulating LH was not involved in the initiation of dominance (inhibition of other follicles by the largest follicle) but was required for the continued growth of the largest follicle after or concurrently with its initial expression of dominance.

Most Compositae (Asteraceae) are descendants of a paleohexaploid and all share a paleotetraploid ancestor with the Calyceraceae

Abstract: Premise of the study Like many other flowering plants, members of the Compositae (Asteraceae) have a polyploid ancestry. Previous analyses found evidence for an ancient duplication or possibly triplication in the early evolutionary history of the family. We sought to better place this paleopolyploidy in the phylogeny and assess its nature. Methods We sequenced new transcriptomes for Barnadesia, the lineage sister to all other Compositae, and four representatives of closely related families. Using a recently developed algorithm, MAPS, we analyzed nuclear gene family phylogenies for evidence of paleopolyploidy. Key results We found that the previously recognized Compositae paleopolyploidy is also in the ancestry of the Calyceraceae. Our phylogenomic analyses uncovered evidence for a successive second round of genome duplication among all sampled Compositae except Barnadesia. Conclusions Our analyses of new samples with new tools provide a revised view of paleopolyploidy in the Compositae. Together with results from a high density Lactuca linkage map, our results suggest that the Compositae and Calyceraceae have a common paleotetraploid ancestor and that most Compositae are descendants of a paleohexaploid. Although paleohexaploids have been previously identified, this is the first example where the paleotetraploid and paleohexaploid lineages have survived over tens of millions of years. The complex polyploidy in the ancestry of the Compositae and Calyceraceae represents a unique opportunity to study the long-term evolutionary fates and consequences of different ploidal levels.

Shannon entropy of brain functional complex networks under the influence of the psychedelic Ayahuasca

Abstract: The entropic brain hypothesis holds that the key facts concerning psychedelics are partially explained in terms of increased entropy of the brain’s functional connectivity. Ayahuasca is a psychedelic beverage of Amazonian indigenous origin with legal status in Brazil in religious and scientific settings. In this context, we use tools and concepts from the theory of complex networks to analyze resting state fMRI data of the brains of human subjects under two distinct conditions: (i) under ordinary waking state and (ii) in an altered state of consciousness induced by ingestion of Ayahuasca. We report an increase in the Shannon entropy of the degree distribution of the networks subsequent to Ayahuasca ingestion. We also find increased local and decreased global network integration. Our results are broadly consistent with the entropic brain hypothesis. Finally, we discuss our findings in the context of descriptions of “mind-expansion” frequently seen in self-reports of users of psychedelic drugs.