Evolutionary history of chromosome 11 featuring four distinct centromere repositioning events in Catarrhini

Panels of BAC clones used in FISH experiments allow a detailed definition of chromosomal marker arrangement and orientation during evolution. This approach has disclosed the centromere repositioning phenomenon, consisting in the activation of a novel, fully functional centromere in an ectopic location, concomitant with the inactivation of the old centromere. In this study, appropriate panels of BAC clones were used to track the chromosome 11 evolutionary history in primates and nonprimate boreoeutherian mammals. Chromosome 11 synteny was found to be highly conserved in both primate and boreoeutherian mammalian ancestors. Amazingly, we detected four centromere repositioning events in primates (in Old World monkeys, in gibbons, in orangutans, and in the Homo-Pan-Gorilla (H-P-G) clade ancestor), and one in Equidae. Both H-P-G and Lar gibbon novel centromeres were flanked by large duplicons with high sequence similarity. Outgroup species analysis revealed that this duplicon was absent in phylogenetically more distant primates. The chromosome 11 ancestral centromere was probably located near the HSA11q telomere. The domain of this inactivated centromere, in humans, is almost devoid of segmental duplications. An inversion occurred in chromosome 11 in the common ancestor of H-P-G. A large duplicon, again absent in outgroup species, was found located adjacent to the inversion breakpoints. In Hominoidea, almost all the five largest duplicons of this chromosome appeared involved in significant evolutionary architectural changes.     

Hop/STI1 modulates retinal proliferation and cell death independent of PrPC

Hop/STI1 is a co-chaperone adaptor protein for Hsp70/Hsp90 complexes. Hop/STI1 is found extracellularly and modulates cell death and differentiation through interaction with the prion protein (PrP(C)). Here, we investigated the expression of hop/STI1 and its role upon cell proliferation and cell death in the developing retina. Hop/STI1 is more expressed in developing rat retina than in the mature tissue. Hop/STI1 blocks retinal cell death in the neuroblastic layer (NBL) in a PrP(C) dependent manner, but failed to protect ganglion cells against axotomy-induced cell death. An antibody raised against hop/STI1 (alpha-STI1) blocked both ganglion cell and NBL cell death independent of PrP(C). cAMP/PKA, ERK, PI3K and PKC signaling pathways were not involved in these effects. Hop/STI1 treatment reduced proliferation, while alpha-STI1 increased proliferation in the developing retina, both independent of PrP(C). We conclude that hop/STI1 can modulate both proliferation and cell death in the developing retina independent of PrP(C).     

Thermogenic activity of Ca2+-ATPase from skeletal muscle heavy sarcoplasmic reticulum: the role of ryanodine Ca2+ channel

The sarcoplasmic reticulum Ca(2+) ATPase 1 (SERCA 1) is able to handle the energy derived from ATP hydrolysis in such a way as to determine the parcel of energy that is used for Ca(2+) transport and the fraction that is converted into heat. In this work we measured the heat production by SERCA 1 in the two sarcoplasmic reticulum (SR) fractions: the light fraction (LSR), which is enriched in SERCA and the heavy fraction (HSR), which contains both the SERCA and the ryanodine Ca(2+) channel. We verified that although HSR cleaved ATP at faster rate than LSR, the amount of heat released during ATP hydrolysis by HSR was smaller than that measured by LSR. Consequently, the amount of heat released per mol of ATP cleaved (DeltaH(cal)) by HSR was lower compared to LSR. In HSR, the addition of 5 mM Mg(2+) or ruthenium red, conditions that close the ryanodine Ca(2+) channel, promoted a decrease in the ATPase activity, but the amount of heat released during ATP hydrolysis remained practically the same. In this condition, the DeltaH(cal) values of ATP hydrolysis increased significantly. Neither Mg(2+) nor ruthenium red had effect on LSR. Thus, we conclude that heat production by SERCA 1 depends on the region of SR in which the enzyme is inserted and that in HSR, the DeltaH(cal) of ATP hydrolysis by SERCA 1 depends on whether the ryanodine Ca(2+) channel is opened or closed.     

Evidence of amino acid diversity-enhancing selection within humans and among primates at the candidate sperm-receptor gene PKDREJ

Sperm-egg interaction is a crucial step in fertilization, yet the identity of most interacting sperm-egg proteins that mediate this process remains elusive. Rapid evolution of some fertilization proteins has been observed in a number of species, including evidence of positive selection in the evolution of components of the mammalian egg coat. The rapid evolution of the egg-coat proteins could strongly select for changes on the sperm receptor, to maintain the interaction. Here, we present evidence that positive selection has driven the evolution of PKDREJ, a candidate sperm receptor of mammalian egg-coat proteins. We sequenced PKDREJ from a panel of 14 primates, including humans, and conducted a comparative maximum-likelihood analysis of nucleotide changes and found evidence of positive selection. An additional panel of 48 humans was surveyed for nucleotide polymorphisms at the PKDREJ locus. The regions predicted to have been subject to adaptive evolution among primates show several amino acid polymorphisms within humans. The distribution of polymorphisms suggests that balancing selection may maintain diverse PKDREJ alleles in some populations. It remains unknown whether there are functional differences associated with these diverse alleles, but their existence could have consequences for human fertility.     

Sanionins: anti-inflammatory and antibacterial agents with weak cytotoxicity from the Antarctic moss Sanionia georgico-uncinata

Sanionins A (1) and B (2) were isolated from the moss Sanionia georgico-uncinata, collected on the Antarctic Livingston Island. The compounds 1 and 2 were purified by solvent extraction, silica gel column chromatography, and preparative HPLC, consecutively. The structures of the both compounds were elucidated by 1D and 2D NMR experiments and mass spectrometric investigations. These compounds showed activity against important Gram-positive pathogens, such as mycobacteria, multiresistant staphylococci, and vancomycin resistant enterococci. This activity is combined with antiinflammatoric activity and low cytotoxicity.     

A new cyanobacterial species with a protective effect on lettuce grown under salinity stress: Envisaging sustainable agriculture practices

Journal of Applied Phycology - In this work, a new terrestrial cyanobacterial species, Oculatella lusitanica LEGE 161147, was isolated and characterized using a polyphasic approach....     

Dormancy and viability of Ferocactus peninsulae (Cactaceae) seeds

Knowledge on seed dormancy is crucial for the understanding of plant population dynamics, as it controls seed germination and seed bank formation. Dormant seeds have high potential to establish in soil seed banks, but such information within Cactaceae is scarce, although it is essential for conservation programs. The aim of this study was to determine if seeds of Ferocactus peninsulae showed any kind of dormancy and to test their germination capacity after storage. This was assessed with 15 seed sowing experiments done over 4 years with seeds stored under room conditions (20 ± 2°C). We demonstrated the existence of physiological dormancy in F. peninsulae seeds that is broken with an after-ripening period. Germination was low during the first 3 months of storage (d = 0.206) but increased after 10 months of storage (d = 0.654), and seeds maintained their viability at 48 months (d = 0.707). Also, their speed of germination increased with storage time. Ferocactus peninsulae seeds are positively photoblastic, and the requirement for light for germination persisted over all experiments. The results provide crucial information for propagation and conservation research and may allow us to infer that F. peninsulae seeds are able to form a persistent soil seed bank, as they maintained their viability after dormancy is released.     

Seasonal variation of nutritional and antioxidant properties of different Kappaphycus alvarezii strains (Rhodophyta) farmed in Brazil

Journal of Applied Phycology - Antioxidant potential, carbohydrate content, ash, minerals, proteins, and amino acids of Kappaphycus alvarezii farmed along the São Paulo coast, Brazil, were...