The dynamics of intraguild predation in Chrysomya albiceps Wied. (Diptera : Calliphoridae): Interactions between instars and species under different abundances of food

The pattern of larval interaction in blowflies confined with Chrysomya albiceps Wied. and C. rufifacies Maquart can be changed in response to the predatory behaviour of the two species to a contest-type process instead of the scramble competition that usually occurs in blowflies. Facultative predation is a frequent behaviour in C. albiceps and C. rufifacies that occurs as an alternative food source during the larval stage. In this study, we investigated the dynamics of intraguild predation by C. albiceps on other fly species in order to analyse interspecific and intraspecific survival in C. albiceps, C. megacephala and C macellaria Fabricius. The experimental design of the study allowed us to evaluate how factors such as species, density and abundance of food influenced the survival of the calliphorid species. When C albiceps was confined with C megacephala or C macellaria, only adults of C albiceps survived at different larval densities and abundance of food. In addition, the survival of C albiceps was higher in two-species experiments when compared to single species experiments. The implications of these results for the dynamics of C albiceps were discussed.

Population dynamics, life stage and ecological modeling in Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evolutionary dynamics of heterochromatin in the genome of Dichotomius beetles based on chromosomal analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytogenetic Mapping of 5S and 18S rRNAs and H3 Histone Genes in 4 Ancient Proscopiidae Grasshopper Species: Contribution to Understanding the Evolutionary Dynamics of Multigene Families

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evolutionary dynamics of rRNA gene clusters in cichlid fish

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of seasonal dynamics and bioindication potential of macroalgal communities in a polluted tropical stream

Macroalgal communities and environmental variables were analyzed seasonally along a polluted tropical stream in São Paulo State, Brazil, We aimed to improve the knowledge of tropical macroalgal communities, to study the longitudinal and seasonal dynamics of these communities in influenced environments, to evaluate the relationship of algal frequency and abundance with selected environmental variables, and to look for potential macroalgal species indicators. The seasonal abundance pattern was similar to natural or low influenced systems and was mainly determined by rainfall regime. However, community composition was closely related to some chemical water pollution indicators, such as phosphorus and nitrogen compounds. Some species are suggested as potential indicators of organic pollution (e.g. Oscillatoria ornata, Stigeoclonium helveticum and Schizomeris leibleinii), but more detailed studies have to be developed to determine the tolerance limits of these species. on the basis of our results and literature data, the use of occurrence of Oscillatoriales in relation to other orders of Cyanoprokaryota is suggested to be a good indicator of organic pollution in tropical lotic ecosystems.

Short-term successional dynamics of a macroalgal community in a stream from northwestern São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Daily dynamics of photosynthesis of the freshwater red alga Sirodotia delicatula (Batrachospermales, Rhodophyta)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

(D)over-barN interaction from meson-exchange and quark-gluon dynamics

We investigate the (D) over barN interaction at low energies using a meson exchange model supplemented with a short-distance contribution from one-gluon exchange. The model is developed in close analogy to the meson-exchange KN interaction of the Julich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving (D) over bar *N , (D) over bar Delta, and (D) over bar*Delta intermediate states. The short-range part is assumed to receive additional contributions from genuine quark-gluon processes. The predicted cross-sections for (D) over barN for excess energies up to 150MeV are of the same order of magnitude as those for KN but with average values of around 20mb, roughly a factor two larger than for the latter system. It is found that the omega-exchange plays a very important role. Its interference pattern with the rho-exchange, which is basically fixed by the assumed SU(4) symmetry, clearly determines the qualitative features of the (D) over barN interaction - very similiar to what happens also for the KN system.

Population dynamics of Petrochirus diogenes (Crustacea, Anomura, Diogenidae) in the Ubatuba region, São Paulo, Brazil

This work examines the population dynamics of Petrochirus diogenes in the Ubatuba region (São Paulo, Brazil), focusing on size frequency distribution, sex ratio, and reproductive and recruitment period. Collections were made with two double-rig nets in the years 1993-1996. The 799 individuals obtained were separated into 14 size classes based on the length of the cephalothoracic shield. The shield size varied from 5.4 to 40.0 mm in males and from 5.7 to 32.1 mm in females. The size frequency distribution was unimodal for both sexes. Only small oscillations occurred in the sex ratio until the seventh size class, followed by preponderance of males. This suggests a standard pattern for the sex ratio in P. diogenes. As males were found in the largest size classes, they present a clear sexual dimorphism. This characteristic can be considered as a selective advantage, mainly during the mating processes and in the agonistic behavior. Ovigerous females were recorded in the spring and summer, indicating seasonal reproduction.

Ovarian follicular dynamics in Nelore breed (Bos indicus) cattle

The most common beef cattle raised in Brazil is the Nelore breed (Bos indicus). Information obtained by ultrasonography on follicular growth in Bos taurus cattle has been accumulating rapidly. However, there are few publications to date on follicular development in Bos indicus breeds. The follicular dynamics in Nelore heifers and cows during natural or prostaglandin (PG)-induced estrous cycle were studied. From the detection of estrus onward, all animals were examined daily by ultrasonography for one (n=35) or two (n=10) consecutive estrous cycles. The follicular dynamic in Nelore cattle was characterized by the predominance of 2 follicular waves in the cows (83.3%, n=18, P<0.05) and 3 waves in the heifers (64.7%, n=16, P<0.05). Most of the cattle observed over 2 consecutive estrous cycles presented the same pattern of follicular waves in the first and second cycle, and only 30% showed variation in the number of waves from one cycle to the other. Most of the follicular parameters analyzed were not affected by PG treatment or age but were altered by follicular waves. Consequently, data on cows and heifers were combined according to the number of follicular waves. The ovulatory follicle was larger than the other dominant follicles (P<0.05), and the ovulatory wave was shorter than the preceding waves (P<0.05). The interovulatory interval was longer in animals showing 3 waves than those exhibiting 2 waves (P<0.05). Maximum diameter of the dominant follicle (around 11 mm) and of the corpus luteum (CL, approximately 17 mm) were smatter than those reported for European breeds. In conclusion, the results demonstrate that although the dominant follicle and corpus luteum are smaller than in European breeds, the follicular dynamics in Nelore cattle were similar to those observed in European breeds and were characterized by 2 or 3 follicular waves for cows and heifers, respectively, during the natural or prostaglandin-induced estrous cycle. (C) 1997 by Elsevier B.V.

Population dynamics of Ectatomma planidens (Hymenoptera: Formicidae) under laboratory conditions

The ant Ectatomma planidens belongs to the subfamily Ectatomminae and it is abundantly found in the Neotropical region. Five colonies of such species were studied regarding their population dynamics in the laboratory, aiming to generate life tables and determine the entropy. The life expectancy curve of the workers indicated that in the first age interval, the value of e x = 142.55 approached the mean longevity of such workers (188.23 ± 110.99 days). Upon reaching this mean longevity, there was a greater decline in the life expectancy, which tends to decrease gradually with the time. The value found for entropy was H = 0.739 (between 0.5 and 1.0), and the survival pattern of these individuals was characterized by high mortality in the first intervals and growing life expectancy as time went by.

Spurious shifts in the pattern of diurnal variation of sea level pressure of reanalysis datasets

The main purpose of this work is to report the presence of spurious discontinuities in the pattern of diurnal variation of sea level pressure of the three reanalysis datasets from: the National Centers for Environmental Prediction (NCEP) and National Center for Atmospheric Science (R1), the NCEP and Department of Energy (R2), and the European Centre for Medium Range Weather Forecasting (ERA-40). Such discontinuities can be connected to the major changes in the global observing system that have occurred throughout reanalyses years. In the R1, the richest period in discontinuities is 1956-1958, coinciding with the start of modern radiosonde observation network. Rapid increase in the density of surface-based observations from 1967 also had an important impact on both R1 and ERA-40, with larger impact on R1. The reanalyses show discontinuities in the 1970s related to the assimilation of radiances measured by the Vertical Temperature Profile Radiometer and TIROS-N Operational Vertical Sounders onboard satellites. In the ERA-40, which additionally assimilated Special Sensor Microwave/Imager data, there are discontinuities in 1987-1989. The R1 also presents further discontinuities, in 1988-1993 likely connected to replacement/introduction of NOAA-series satellites with different biases, and to the volcanic eruption of Mount Pinatubo in June 1991, which is known to have severely affected measurements of infrared radiances for several years. The discontinuities in 1996-1998 might be partially connected to change in the type of radiosonde, from VIZ-B to VIZ-B2. The R2, which covers only satellite era (1979-on), shows discontinuities mainly in 1992, 1996-1997, and 2001. The discontinuities in 1992 and 2001 might have been caused by change in the satellite measurements and those in 1996-1997 by some changes in land-based observations network. © 2012 Springer-Verlag.

On the unzipping mechanisms of carbon nanotubes: Insights from reactive molecular dynamics simulations

Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for the controlled and large-scale production of graphene nanoribbons (GNR). These structures are considered of great importance for the development of nanoelectronics because of its dimensions and intrinsic nonzero band gap value. Despite many years of investigations some details on the dynamics of the CNT fracture/unzipping processes remain unclear. In this work we have investigated some of these process through molecular dynamics simulations using reactive force fields (ReaxFF), as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. We considered multi-walled CNTs of different dimensions and chiralities and under induced mechanical stretching. Our preliminary results show that the unzipping mechanisms are highly dependent on CNT chirality. Well-defined and distinct fracture patterns were observed for the different chiralities. Armchair CNTs favor the creation of GNRs with well-defined armchair edges, while zigzag and chiral ones produce GNRs with less defined and defective edges. © 2012 Materials Research Society.

Dynamics of DNA Methylation during Early Development of the Preimplantation Bovine Embryo

There is species divergence in control of DNA methylation during preimplantation development. The exact pattern of methylation in the bovine embryo has not been established nor has its regulation by gender or maternal signals that regulate development such as colony stimulating factor 2 (CSF2). Using immunofluorescent labeling with anti-5-methylcytosine and embryos produced with X-chromosome sorted sperm, it was demonstrated that methylation decreased from the 2-cell stage to the 6-8 cell stage and then increased thereafter up to the blastocyst stage. In a second experiment, embryos of specific genders were produced by fertilization with X- or Y-sorted sperm. The developmental pattern was similar to the first experiment, but there was stage × gender interaction. Methylation was greater for females at the 8-cell stage but greater for males at the blastocyst stage. Treatment with CSF2 had no effect on labeling for DNA methylation in blastocysts. Methylation was lower for inner cell mass cells (i.e., cells that did not label with anti-CDX2) than for trophectoderm (CDX2-positive). The possible role for DNMT3B in developmental changes in methylation was evaluated by determining gene expression and degree of methylation. Steady-state mRNA for DNMT3B decreased from the 2-cell stage to a nadir for D 5 embryos >16 cells and then increased at the blastocyst stage. High resolution melting analysis was used to assess methylation of a CpG rich region in an intronic region of DNMT3B. Methylation percent decreased between the 6-8 cell and the blastocyst stage but there was no difference in methylation between ICM and TE. Results indicate that DNA methylation undergoes dynamic changes during the preimplantation period in a manner that is dependent upon gender and cell lineage. Developmental changes in expression of DNMT3B are indicative of a possible role in changes in methylation. Moreover, DNMT3B itself appears to be under epigenetic control by methylation. © 2013 Dobbs et al.