Genetic characterization of residual <Emphasis Type="Italic">Triatoma infestans</Emphasis> populations from Brazil by microsatellite

In spite of long-term efforts to eliminate Triatoma infestans (Klug 1834) from Brazil, residual foci still persist in the states of Bahia and Rio Grande do Sul. Data on the genetic variability and structuring of these populations are however lacking. Using nine microsatellite loci, we characterized one residual T. infestans population from Bahia and four from Rio Grande do Sul, and compared them with bugs originally from an older focus in São Paulo; 224 bugs were genotyped. The number of alleles per locus ranged from 5 to 11. Observed and expected heterozygosities per locus ranged, respectively, from 0 to 0.786 and from 0 to 0.764. Significant departures from Hardy–Weinberg equilibrium, mainly due to heterozygote deficits, were detected in all loci and in most populations. Global indices estimated by AMOVA were: Fis was 0.37; Fst was 0.28; and Fit was 0.55; overall indices with p?=?0.00 indicated substantial differentiation. Inter-population Fst ranged from 0.118 to 0.562, suggesting strong genetic structuring and little to no gene flow among populations. Intra-population Fis ranged from 0.301 to 0.307. Inbreeding was apparent in all populations except that from Bahia—which might be either linked by gene flow to nearby unsampled populations or part of a relatively large local population. The overall pattern of strong genetic structuring among pyrethroid-susceptible residual T. infestans populations suggests that their persistence is probably due to operational control failures. Detection and elimination of such residual foci is technically feasible and must become a public health priority in Brazil.     

Unilateral ovarian absence in a Black‐headed Squirrel Monkey (Saimiri vanzolinii Ayres, 1985), a threatened neotropical primate species

Ovarian agenesis is an unusual anomaly with traumatic or congenital origin. In the present case report, we describe our findings in a senile S. vanzolinii female. As this neotropical primate species is listed as vulnerable, with limited geographic distribution in the Brazilian Amazonia, ovarian agenesis may be an important finding to be reported.     

Does Resource Availability Affect the Diet and Behavior of the Vulnerable Squirrel Monkey, <Emphasis Type="Italic">Saimiri vanzolinii</Emphasis>?

Seasonal changes in food availability influence the behavior and diet of primates, and an understanding of dietary changes is important for the development of informed conservation plans. Saimiri vanzolinii is a small-bodied, omnivorous squirrel monkey endemic to the floodplain forests in Central Amazonia. It has a restricted distribution of only ca. 870 km² and is classified as Vulnerable. We examined seasonal variation in this species’ diet. We collected phenological (presence and absence of ripe fruits from 205 tree species) and dietary and behavioral data for unhabituated groups of S. vanzolinii on nine 2-km transects in the floodplain forests of Central Amazonia for 2 years, encompassing the high-water and low-water periods. Fruit availability was higher, and the monkeys traveled less and fed more during the high-water than the low-water period. There were no seasonal differences between the high-water and low-water periods in the time spent feeding on fruits, flowers, or arthropods. S. vanzolinii spent more time consuming fruit than arthropods in the high-water period, but this was not the case in the low-water period. These findings suggest that food selection changed between seasons, and S. vanzolinii focused more on fruit in the low-water period, when fruit was less available, than in the high-water period, when fruit was more available. These results support the predictions of the ecological constraints model.     

Life history traits of two dwarf cichlids species in the white waters of the Amazonian floodplain

The reproductive parameters are among the most important life history aspects of fishes influenced by environmental variation. During recent years, the main life history strategies of Amazonian fish species were defined mostly by a set of reproductive parameters. In the present work, we sought to describe important life history parameters, in particular on reproductive characteristics of Apistogramma agassizii and Apistogramma bitaeniata, found in floodplain lakes of the Brazilian Amazonia. The species presented a positive sexual dimorphism, and males were significantly bigger than females. For both sexes, four developmental phase of gonad maturation were detected, and based on those it was possible to identify mature, reproductive specimens throughout the entire period of the study. From the ovaries of mature females, fecundity and spawning type were determined. Low fecundity, short spawning periods, possibly separated only by few months, and total spawning are all good indications that A. agassizii and A. bitaeniata evolved an opportunistic strategy in their life history.     

Dual role of topoisomerase II in centromere resolution and aurora B activity

Chromosome segregation requires sister chromatid resolution. Condensins are essential for this process since they organize an axial structure where topoisomerase II can work. How sister chromatid separation is coordinated with chromosome condensation and decatenation activity remains unknown. We combined four-dimensional (4D) microscopy, RNA interference (RNAi), and biochemical analyses to show that topoisomerase II plays an essential role in this process. Either depletion of topoisomerase II or exposure to specific anti-topoisomerase II inhibitors causes centromere nondisjunction, associated with syntelic chromosome attachments. However, cells degrade cohesins and timely exit mitosis after satisfying the spindle assembly checkpoint. Moreover, in topoisomerase II–depleted cells, Aurora B and INCENP fail to transfer to the central spindle in late mitosis and remain tightly associated with centromeres of nondisjoined sister chromatids. Also, in topoisomerase II–depleted cells, Aurora B shows significantly reduced kinase activity both in S2 and HeLa cells. Codepletion of BubR1 in S2 cells restores Aurora B kinase activity, and consequently, most syntelic attachments are released. Taken together, our results support that topoisomerase II ensures proper sister chromatid separation through a direct role in centromere resolution and prevents incorrect microtubule–kinetochore attachments by allowing proper activation of Aurora B kinase.     

BioPEGylation of polyhydroxyalkanoates: influence on properties and satellite-stem cell cycle

The addition of poly(ethylene glycol), PEG, to bioprocessing systems producing polyhydroxyalkanoates (PHAs), has been reported as a means of their molecular weight control and can also support bioPEGylation, resulting in hybrids with amphiphillic properties. However, the study of such natural-synthetic hybrids of PHA-b-PEG is still in its infancy. In this study, we report the influence of bioPEGylation of polyhydroxyoctanoate (PHO) on its physiochemical, material, and biological properties. Consistent with previous studies, bioPEGylation with diethylene glycol (DEG) showed a significant reduction in PHA molecular weight (57%). In comparison to solvent cast films of PHO, PHO-b-DEG films possessed a noticeable X-ray diffraction peak at 9.82 degrees and increased Young's modulus of 11 Gpa (83%). Potential biocompatibility was investigated by measuring the early phase of apoptosis in myoblastic satellite-stem cells (C2C12). Comparative analysis of cell proliferation and progression in the presence of the mcl-PHA and its hybrid showed that the latter induced significant cell cycle progression: the first time a biomaterial has been shown to do so. Microtopographies of the film surfaces demonstrated that these differences were not due to changes in surface morphology; both polymers possessed average surface rugosities of 1.4 +/- 0.2 microm. However, a slight decrease in surface hydrophobicity (3.5 +/- 0.9 degrees) due to the hydrophilic DEG may have exerted an influence. The results support the further study of bioPEGylated PHAs as potential biomaterials in the field of tissue engineering.     

Association of small CAB-like proteins (SCPs) of Synechocystis sp. PCC 6803 with Photosystem II

The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267–276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Galyna Kufryk and Miguel Hernandez-Prieto have contributed equally to this work.     

MAST/Orbit has a role in microtubule-kinetochore attachment and is essential for chromosome alignment and maintenance of spindle bipolarity

Multiple asters (MAST)/Orbit is a member of a new family of nonmotor microtubule-associated proteins that has been previously shown to be required for the organization of the mitotic spindle. Here we provide evidence that MAST/Orbit is required for functional kinetochore attachment, chromosome congression, and the maintenance of spindle bipolarity. In vivo analysis of Drosophila mast mutant embryos undergoing early mitotic divisions revealed that chromosomes are unable to reach a stable metaphase alignment and that bipolar spindles collapse as centrosomes move progressively closer toward the cell center and eventually organize into a monopolar configuration. Similarly, soon after depletion of MAST/Orbit in Drosophila S2 cells by double-stranded RNA interference, cells are unable to form a metaphase plate and instead assemble monopolar spindles with chromosomes localized close to the center of the aster. In these cells, kinetochores either fail to achieve end-on attachment or are associated with short microtubules. Remarkably, when microtubule dynamics is suppressed in MAST-depleted cells, chromosomes localize at the periphery of the monopolar aster associated with the plus ends of well-defined microtubule bundles. Furthermore, in these cells, dynein and ZW10 accumulate at kinetochores and fail to transfer to microtubules. However, loss of MAST/Orbit does not affect the kinetochore localization of D-CLIP-190. Together, these results strongly support the conclusion that MAST/Orbit is required for microtubules to form functional attachments to kinetochores and to maintain spindle bipolarity.     

Cell cycle activation by plant parasitic nematodes

Sedentary nematodes are important pests of crop plants. They are biotrophic parasites that can induce the (re)differentiation of either differentiated or undifferentiated plant cells into specialized feeding cells. This (re)differentiation includes the reactivation of the cell cycle in specific plant cells finally resulting in a transfer cell-like feeding site. For growth and development the nematodes fully depend on these cells. The mechanisms underlying the ability of these nematodes to manipulate a plant for its own benefit are unknown. Nematode secretions are thought to play a key role both in plant penetration and feeding cell induction. Research on plant-nematode interactions is hampered by the minute size of cyst and root knot nematodes, their obligatory biotrophic nature and their relatively long life cycle. Recently, insights into cell cycle control in Arabidopsis thaliana in combination with reporter gene technologies showed the differential activation of cell cycle gene promoters upon infection with cyst or root knot nematodes. In this review, we integrate the current views of plant cell fate manipulation by these sedentary nematodes and made an inventory of possible links between cell cycle activation and local, nematode-induced changes in auxin levels.