Chromosomal similarities and differences among four Neotropical Elateridae (Conoderini and Pyrophorini) and other related species, with comments on the NOR patterns in Coleoptera

This work deals with the comparative cytogenetic analysis of four Neotropical Elateridae species and reviews the nucleolar organizer region (NOR) patterns on Coleoptera chromosomes, for the first time. The cytogenetic characterization of Conoderus malleatus (Conoderini), Pyrearinus candelarius, Pyrophorus divergens and Pyrophorus punctatissimus (Pyrophorini) was accomplished through the study of mitotic and meiotic cells submitted to standard (Giemsa) and differential staining [silver impregnation and GC-specific chromomycin A 3 (CMA 3) plus AT-specific 4′-6-diamidino-2-phenylindole (DAPI) fluorochromes]. The analysis of spermatogonial cells revealed the diploid numbers: 2n = 17 in C. malleatus and 2n = 15 in P. candelarius, P. divergens and P. punctatissimus. In these species, the X0 type sex-determination system and the acrocentric morphology of almost all chromosomes were observed. The study of meiotic cells of the four species revealed the occurrence of total synapsis between the autosomes, the presence of one terminal or interstitial chiasma in the majority of the bivalents, and the reductional behaviour and regular segregation of all chromosomes. Although the three Pyrophorini species demonstrated many similar karyotypical characteristics, there was one discrepancy, which was noted in the diplotene cells and concerns the number of bivalents with two chiasmata; P. candelarius only presented one bivalent, P. divergens showed two bivalents and P. punctatissimus exhibited up to four bivalents with two chiasmata. Testicular cells impregnated with silver nitrate demonstrated two terminal NORs located on the fourth autosomal pair of the Conoderini species and on the second autosomal pair of the three Pyrophorini representatives. Use of CMA 3/distamycin A (DA)/DAPI staining on the P. candelarius and P. punctatissimus chromosomes revealed that the CMA 3 labelled regions were coincident with the NORs. The main strategies of karyotypical differentiation that have occurred among the four Elateridae species and other related species, and the general trends of the NOR shifts during Coleoptera chromosomal evolution are discussed in this work. © 2007 The Authors.

Alkaline phosphatase localization in golden hamster epididymidis: A biochemical and histochemical investigation

The aim of this study was to determine alkaline phosphatase (ALP; E.C. 3.1.3.1) activity and major expression in homogenates obtained from different regions of Golden hamster epididymis, comprising the initial segment, head, body and tail, with concomitant research of this enzyme localization and activity in samples of tissues. These were collected from the same regions and investigated by histochemical conventional study performed on frozen histological sections. No significant differences in mean ALP activity, reported as U.100 mg-1 of tissue, were observed among the biological specimens collected from the epididymidis initial segment (0.92 ± 0.28 U.100 mg-1 tissue), head (1.07 ± 0.67 U.100 mg-1 tissue) and body (0.77 ± 0.23 U.100 mg-1 tissue). However, mean ALP activity was significantly higher in the epididymal tail (8.94 ± 0.40 U.100 mg-1 tissue) compared with the precedent segments. The findings suggested that ALP plays a significant role in the tail of the Golden hamster epididymidis, mediating androgenic segregation necessary to maintain the epithelial integrity. Furthermore, ALP acts on active transport of substances between the luminal fluid and spermatozoon membrane, and contrariwise. Thus, the high concentration of ALP in the epididymal tail helps to indicate the importance of this enzyme in the metabolism and maintenance of spermatozoa maturation and storage into the epididymidis luminal compartment, perhaps directly influencing the normal reproductive morphophysiology.

Heat transfer in a packed sugar cane bagasse bed

Heat transfer in a packed bed of sugar cane bagasse, which is a potential biofuel used in cars and industries, percolated with air flow was studied. The fibers were washed, sieved, oven dried, and afterwards moisture content was adjusted to 4 and 47%. The relative humidity of the air, packing bed technique, and the initial moisture content of the porous media did not have a significant effect on the outlet temperature of the bed. Air flow rate influenced the averaged radial temperature profile, but not the temperature measured at the nearest position to the tube wall. At the end of the experiments, moisture segregation was observed, the lower bed depths being drier than the higher ones. This is an abstract of a paper presented at the 18th International Congress of Chemical Process Engineering (Praque, Czech Republic 8/24-28/2008).

Population dynamics of the seabob shrimp Xiphopenaeus kroyeri (Dendrobranchiata, Penaeidae) in south-eastern Brazil

The population dynamics, including the sex ratio, reproductive period, individual growth and longevity, and population structure of the shrimp Xiphopenaeus kroyeri, are described. The shrimps were collected monthly from July 2005 to June 2007 at four sites in Ubatuba Bay, Brazil. The salinity, temperature, depth, organic matter content and sediment grain size were measured at each site. Specimens were quantified and sexed, their carapace length measured and their gonads were classified according to the stage of maturation. A von Bertalanffy model was used to estimate the individual growth, and longevity was calculated using its inverted formula. In total, 6 470 individuals were examined and the number of males and females differed significantly in favour of females. During some periods, the segregation could be related to the reproductive period. Reproductive females were captured throughout the sampled period, and there were biannual peaks that were followed by peaks of juveniles. Carapace growth was less for males than for females, which is likely related to oocyte production and the higher fecundity of the females. The higher probability of female capture can be related to their longer foraging to sustain the enhanced food requirement during the ovarian maturation period. © 2013 Copyright NISC (Pty) Ltd.

Mixing Eucalyptus and Acacia trees leads to fine root over-yielding and vertical segregation between species

The consequences of diversity on belowground processes are still poorly known in tropical forests. The distributions of very fine roots (diameter <1 mm) and fine roots (diameter <3 mm) were studied in a randomized block design close to the harvest age of fast-growing plantations. A replacement series was set up in Brazil with mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and a mixture with the same stocking density and 50 % of each species (50A:50E). The total fine root (FR) biomass down to a depth of 2 m was about 27 % higher in 50A:50E than in 100A and 100E. Fine root over-yielding in 50A:50E resulted from a 72 % rise in E. grandis fine root biomass per tree relative to 100E, whereas A. mangium FR biomass per tree was 17 % lower than in 100A. Mixing A. mangium with E. grandis trees led to a drop in A. mangium FR biomass in the upper 50 cm of soil relative to 100A, partially balanced by a rise in deep soil layers. Our results highlight similarities in the effects of directional resources on leaf and FR distributions in the mixture, with A. mangium leaves below the E. grandis canopy and a low density of A. mangium fine roots in the resource-rich soil layers relative to monospecific stands. The vertical segregation of resource-absorbing organs did not lead to niche complementarity expected to increase the total biomass production. © 2012 Springer-Verlag Berlin Heidelberg.

Meiotic pairing of B chromosomes, multiple sexual system, and Robertsonian fusion in the red brocket deer Mazama americana (Mammalia, Cervidae)

Deer species of the genus Mazama show significant inter and intraspecific chromosomal variation due to the occurrence of rearrangements and B chromosomes. Given that carriers of aneuploidies and structural rearrangements often show anomalous chromosome pairings, we here performed a synaptonemal complex analysis to study chromosome pairing behavior in a red brocket deer (Mazama americana) individual that is heterozygous for a Robertsonian translocation, is a B chromosome carrier, and has a multiple sex chromosome system (XY1Y2). The synaptonemal complex in spermatocytes showed normal chromosome pairings for all chromosomes, including the autosomal and sex trivalents. The electromicrographs showed homology among B chromosomes since they formed bivalents, but they also appeared as univalents, indicating their anomalous behavior and non-Mendelian segregation. Thus, synaptonemal complex analysis is a useful tool to evaluate the role of B chromosomes and rearrangements during meiosis on the intraspecific chromosomal variation that is observed in the majority of Mazama species. © FUNPEC-RP.

Vanadium-doped TiO2 anatase nanostructures: the role of V in solid solution formation and its effect on the optical properties

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

Leishmania amazonensis Promastigotes Present Two Distinct Modes of Nucleus and Kinetoplast Segregation during Cell Cycle

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

Intraspecific, interspecific, and seasonal differences in the diet of three mid-sized carnivores in a large neotropical wetland

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phylogeny and micro-habitats utilized by lizards determine the composition of their endoparasites in the semiarid Caatinga of Northeast Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Short communication: Variable number of tandem repeat polymorphisms in DGAT1 gene of buffaloes (Bubalus bubalis) is associated with milk constituents

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

Spurious transients of projection methods in microflow simulations

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

Tolerance to high temperature in F-5 inbred lines of tomato

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Single-cell expression profiling reveals a dynamic state of cardiac precursor cells in the early mouse embryo

In the early vertebrate embryo, cardiac progenitor/precursor cells (CPs) give rise to cardiac structures. Better understanding their biological character is critical to understand the heart development and to apply CPs for the clinical arena. However, our knowledge remains incomplete. With the use of single-cell expression profiling, we have now revealed rapid and dynamic changes in gene expression profiles of the embryonic CPs during the early phase after their segregation from the cardiac mesoderm. Progressively, the nascent mesodermal gene Mesp1 terminated, and Nkx2-5+/Tbx5+ population rapidly replaced the Tbx5low+ population as the expression of the cardiac genes Tbx5 and Nkx2-5 increased. At the Early Headfold stage, Tbx5-expressing CPs gradually showed a unique molecular signature with signs of cardiomyocyte differentiation. Lineage-tracing revealed a developmentally distinct characteristic of this population. They underwent progressive differentiation only towards the cardiomyocyte lineage corresponding to the first heart field rather than being maintained as a progenitor pool. More importantly, Tbx5 likely plays an important role in a transcriptional network to regulate the distinct character of the FHF via a positive feedback loop to activate the robust expression of Tbx5 in CPs. These data expands our knowledge on the behavior of CPs during the early phase of cardiac development, subsequently providing a platform for further study.

Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae)

Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation.