PfAlbas constitute a new eukaryotic DNA/RNA-binding protein family in malaria parasites

In Plasmodium falciparum, perinuclear subtelomeric chromatin conveys monoallelic expression of virulence genes. However, proteins that directly bind to chromosome ends are poorly described. Here we identify a novel DNA/RNA-binding protein family that bears homology to the archaeal protein Alba (Acetylation lowers binding affinity). We isolated three of the four PfAlba paralogs as part of a molecular complex that is associated with the P. falciparum-specific TARE6 (Telomere-Associated Repetitive Elements 6) subtelomeric region and showed in electromobility shift assays (EMSAs) that the PfAlbas bind to TARE6 repeats. In early blood stages, the PfAlba proteins were enriched at the nuclear periphery and partially co-localized with PfSir2, a TARE6-associated histone deacetylase linked to the process of antigenic variation. The nuclear location changed at the onset of parasite proliferation (trophozoite-schizont), where the PfAlba proteins were also detectable in the cytoplasm in a punctate pattern. Using single-stranded RNA (ssRNA) probes in EMSAs, we found that PfAlbas bind to ssRNA, albeit with different binding preferences. We demonstrate for the first time in eukaryotes that Alba-like proteins bind to both DNA and RNA and that their intracellular location is developmentally regulated. Discovery of the PfAlbas may provide a link between the previously described subtelomeric non-coding RNA and the regulation of antigenic variation.     

New thiazole carboxamides as potent inhibitors of Akt kinases

A new series of 2-substituted thiazole carboxamides were identified as potent pan inhibitors against all three isoforms of Akt (Akt1, Akt2 and Akt3) by systematic optimization of weak screening hit N-(1-amino-3-phenylpropan-2-yl)-2-phenylthiazole-5-carboxamide (1). One of the most potent compounds, 5m, inhibited the kinase activities of Akt1, Akt2 and Akt3 with IC(50) values of 25, 196 and 24nM, respectively. The compound also potently inhibited the phosphorylation of downstream MDM2 and GSK3β proteins, and displayed strongly antiproliferative activity in prostate cancer cells. The inhibitors might serve as lead compounds for further development of novel effective anticancer agents.     

Plagioscion squamosissimus (Sciaenidae) and Parachromis managuensis (Cichlidae): a threat to native fishes of the Doce River in Minas Gerais, Brazil

The middle section of the lake basin of the Doce River in Minas Gerais State, Brazil is plagued by grave environmental problems, including the introduction of non-native fish, which reduces the biodiversity of this region. This study reports the presence of two newly-detected non-native species in the Doce River Basin. Sampling efforts included gill nets with mesh size of 3 to 12 mm (measured diagonally) and trawling nets, both of which were used in independent field campaigns in 2002 and 2011. The two new invasive Perciform fishes, Plagioscion squamosissimus (Heckel 1840) and Parachromis managuensis (Günther 1867) were collected in Caratinga and Rio Doce municipalities. These records and other reports on non-native fishes suggest favorable environmental conditions for the establishment of invasive species in this drainage. These invasive species have behavior and diet observed in other wide distribution exotic fish of Rio Doce Basin representing a threat to the 77 native fishes of this region, 37 of which are endangered.     

A new species of Fuziidae (Insecta, Blattida) from the Inner Mongolia, China

A new species attributed to the genus Parvifuzia Guo & Ren, 2011, Parvifuzia peregrinasp. n., is described from the Middle Jurassic Jiulongshan Formation of Daohugou Village, Inner Mongolia, China. This new species, with apex of wing almost reaching the end of the abdomen and forewing venation with 30-32 veins at margin, broadens the diversity of Parvifuzia. This new species, with strongly curved cerci, could tightly clasp female and complete copulation more efficiently, same as other members of the family Fuziidae.     

Direct and indirect landscape effects on Quercus ilex regeneration in heterogeneous environments

Understanding how plant–animal interactions shape plant regeneration is traditionally examined at local scales. In contrast, landscape ecologists working at regional scales often have to infer the mechanisms underlying vegetation patterns. In this study, we empirically explored how landscape attributes (patch connectivity, size, shape, irradiance, slope, and elevation) influence biotic interactions in 1- and 2-year seedlings and saplings of Quercus ilex. We combined field data and GIS-based information under a set of five connectivity scenarios, presuming low, intermediate, and long-distance seed dispersal. Our study emphasizes that landscape, apart from its direct effects on plants, plays a key, albeit indirect, role in plant demography through its effects on seed dispersers and predators. Moreover, the effects of landscape on recruitment differed between plant life stages. One-year seedlings and saplings appear to depend more on plant–animal interactions, while 2-year seedlings depend more on irradiance. Differences in patch connectivity resulted in direct and indirect effects on biotic interactions, which, in turn, produced contrasting positive and negative effects on regeneration at different stages of the life cycle. While jays and wild boars seem crucial to all life stages and most of the connectivity scenarios, rodents and herbivores affected only 1-year seedlings and saplings, respectively, and only a few of the connectivity scenarios. By simultaneously including an ensemble of explanatory factors, our study emphasizes that regeneration depends on a set of key drivers, both abiotic (i.e. irradiance) and biotic (i.e. jays and wild boars), whose effects are greatly modulated by landscape traits.     

Functional Analyses of the Plant Photosystem I-Light-Harvesting Complex II Supercomplex Reveal That Light-Harvesting Complex II Loosely Bound to Photosystem II Is a Very Efficient Antenna for Photosystem I in State II

State transitions are an important photosynthetic short-term response that allows energy distribution balancing between photosystems I (PSI) and II (PSII). In plants when PSII is preferentially excited compared with PSI (State II), part of the major light-harvesting complex LHCII migrates to PSI to form a PSI-LHCII supercomplex. So far, little is known about this complex, mainly due to purification problems. Here, a stable PSI-LHCII supercomplex is purified from Arabidopsis thaliana and maize (Zea mays) plants. It is demonstrated that LHCIIs loosely bound to PSII in State I are the trimers mainly involved in state transitions and become strongly bound to PSI in State II. Specific Lhcb1-3 isoforms are differently represented in the mobile LHCII compared with S and M trimers. Fluorescence analyses indicate that excitation energy migration from mobile LHCII to PSI is rapid and efficient, and the quantum yield of photochemical conversion of PSI-LHCII is substantially unaffected with respect to PSI, despite a sizable increase of the antenna size. An updated PSI-LHCII structural model suggests that the low-energy chlorophylls 611 and 612 in LHCII interact with the chlorophyll 11145 at the interface of PSI. In contrast with the common opinion, we suggest that the mobile pool of LHCII may be considered an intimate part of the PSI antenna system that is displaced to PSII in State I.     

Chorionic gonadotropin-like proteins in the obplacental giant cells of the rabbit

Diabetes mellitus was induced in 40 male C57BL6 mice by injection of a low dose of streptozocin (45 mg/kg body weight) on 5 consecutive days. Twenty four of the mice were immunosuppressed by administration of 1.5 mg FK506/kg body weight daily for 10, 15, 18 and 24 days. Administration of FK506 almost completely inhibited the streptozocin-induced islet damage, and consequently glycaemia remained normal. In FK506-treated animals any inflammatory infiltrate was very sparse and was limited to the vascular pole of the islets. Immunocytochemical results demonstrated that infiltrating cells were Ia-immunoreactive, but were not activated. Ultrastructural observations confirmed the absence of B cell necrosis and degranulation in FK506-treated mice; the few infiltrating elements encountered did not contain phagocytic vesicles or show other signs of activation.     

Effects of habitat fragmentation on provisioning rates, diet and breeding success in two species of tit (great tit and blue tit)

The aim of this study was to examine the effects of forest fragmentation on the ability of parent birds to provide their young with an adequate food supply. To examine whether prey population densities of the great tit (Parus major L.) and the blue tit (P. caeruleus L.) vary between study areas in different forest size classes we compared provisioning rates and chick diet and related these parameters to breeding success. We filmed 217 nests over two breeding seasons and collected data on frass fall as a general estimate of caterpillar availability. Nests which were attended by none or one parent only during filming (n = 46) were excluded from the analyses. In both years and for both species feeding rates were highest in the smallest fragments and lowest in the large forest. There was also a suggestion that differences in feeding rates between areas vary between years. We found no consistent tendency for prey size to change with forest size, although both species brought slightly smaller prey items to the nest in the smallest forest fragments and feeding rates correlated negatively with prey size. Caterpillars were the main item fed to nestlings, in both species. We found no evidence to suggest that either frass fall or the proportion of caterpillars in the diet varied with forest size. There was also no correlation between mean frass fall and the total number of caterpillars brought to the nests, in either species. Breeding success, as measured by clutch size, brood size, fledging weight and fledging success, did not differ between the small fragments and the large forest, in either species. There was also no relationship between provisioning rate (as concerns volume of prey fed to nestlings and the quality of chick diet) and breeding success parameters. In conclusion, this study does not suggest suboptimal foraging or breeding conditions in small fragments compared to a nearby large forest, for either species. Received: 23 June 1997 / Accepted: 29 December 1997