A detailed study of the periodate oxidation of sialic acids in glycoproteins

Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland, respectively, can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids. In contrast, the C-8 compounds can be obtained in a maximum yield of about 40%. Under identical conditions,N-glycoloylneuraminic acid is oxidized about 1.5 times faster than theN-acetylated derivative. After release of the sialic acids by acid hydrolysis, the characterization of the oxidation products was carried out by TLC, by GLC and GLC-MS of the corresponding pertrimethylsilyl derivatives, and by 500-MHz¹H-NMR spectroscopy. In addition, molar response factors for GLC analysis and extinction coefficients in the orcinol/Fe³⁺/HCl assay were determined.     

Patterns of divergence during evolution of alpha 1-proteinase inhibitors in mammals

alpha 1-Proteinase inhibitor (alpha 1-PI), a member of the serine proteinase inhibitor superfamily, has a primary role in controlling neutrophil elastase activity within the mammalian circulation. Several studies have indicated that the reactive center region of alpha 1-PI, the amino acid sequence of which is critical to recognition of and binding to target proteinases, is highly divergent within and among species. This appears to be a consequence of accelerated rates of evolution that may have been driven by positive Darwinian selection. In order to examine this and other features of alpha 1-PI evolution in more detail, we have isolated and sequenced cDNAs representing alpha 1- PI mRNAs of the mouse species Mus saxicola and Mus minutoides and have compared these with a number of other mammalian alpha 1-PI mRNAs. Relative to other mammalian mRNAs, the extent of nonsynonymous substitution is generally high throughout the alpha 1-PI mRNA molecule, indicating greater overall rates of amino acid substitution. Within and among mouse species, the 5'-half of the mRNA, but not the 3'-half, has been homogenized by concerted evolution. Finally, the reactive center is under diversifying or positive Darwinian selection in murid rodents (rats, mice) and guinea pigs yet is under purifying selection in primates and artiodactyls. The significance of these findings to alpha 1-PI function and the possible selective forces driving evolution of serpins in general are discussed.      

Communal roosting,thermoregulatory benefits and breeding group size predictability in cooperatively breeding sociable weavers

Extreme temperatures impose energy costs on endotherms through thermoregulation and different adaptations help individuals to cope with these conditions. In social species, communal roosting and huddling are thought to decrease the energetic requirement of thermoregulation under low temperatures. This is likely to represent an important mechanism by which individuals save energy during the coldest parts of the year and hence to represent a non‐breeding benefit of sociality. Here, we investigate the potential thermoregulatory benefits of group living in roosting groups of sociable weavers Philetairus socius, a colonial cooperatively breeding passerine that builds communally a massive nest structure with several independent chambers wherein individuals breed and roost throughout the year. To investigate the benefits of sociality during the non‐breeding season, we studied the thermal environment during roosting in relation to group size. In addition, to understand the link between non‐breeding and breeding sociality in this species we studied group size stability between the pre‐breeding and breeding periods. As expected, we found that the nest chamber's night‐time temperature is strongly related to the number of birds roosting together, especially during cold nights. Specifically, birds in larger groups spent less time below the critical thermal minimum temperature (i.e. the temperature below which energy expenditure increases substantially). They were less exposed to external temperature variations. We also found a positive relationship between the number of birds roosting during winter and the breeding group size, indicating breeding group size predictability. In cooperative breeders such as the sociable weaver, the costs and benefits of sociality are usually studied during the breeding period. This study shows that a better understanding of non‐breeding benefits of group membership and group dynamics between the non‐breeding and breeding periods are necessary for a comprehensive understanding of the benefits of sociality.     

An integrated population model sheds light on the complex population dynamics of a unique colonial breeder

Climate models forecast increasing climatic variation and more extreme events, which could increase the variability in animal demographic rates. More variable demographic rates generally lead to lower population growth and can be detrimental to wild populations, especially if the particular demographic rates affected are those to which population growth is most sensitive. We investigated the population dynamics of a metapopulation of 25 colonies of a semi-arid bird species, the sociable weaver Philetairus socius, and how it was influenced by seasonal weather during 1993–2014. We constructed an integrated population model which estimated population sizes similar to observed population counts, and allowed us to estimate annual fecundity and recruitment. Variance in fecundity contributed most to variance in population growth, which showed no trend over time. No weather variables explained overall demographic variation at the population level. However, a separate analysis of the largest colony showed a clear decline with a high extinction probability (0.05 to 0.33) within 5 years after the study period. In this colony, juvenile survival was lower when summers were hot, and adult survival was lower when winters were cold. Rainfall was also negatively correlated with adult survival. These weather effects could be due to increased physiological demands of thermoregulation and rainfall-induced breeding activity. Our results suggest that the dynamics of the population on the whole are buffered against current weather variation, as individual colonies apparently react in different ways. However, if more and increasingly extreme weather events synchronize colony dynamics, they are likely to have negative effects.     

Secular trends of obesity and cardiovascular risk factors in a Mediterranean population

Objective: To evaluate time trends of obesity, abdominal obesity, and cardiovascular risk factors (CRFs) according to BMI and waist circumference (WC) categories in a Mediterranean population. Research Methods and Procedures: Subjects were Spanish men (n = 2383) and women (n = 2525) 25 to 74 years old, examined in 1994 to 1995 and 1999 to 2000 in two independent population‐based cross‐sectional surveys in the northeast of Spain. Lifestyle measures, CRFs, and anthropometric variables were analyzed. Results: Over the 5 years of the study, mean age‐standardized BMI increased by 1.0 units in men and by 0.8 units in women. At the same time the prevalence of obesity increased from 15.4% to 21.9% in men and from 15.4% to 21.4% in women. An upward trend was observed for WC and abdominal obesity (WC > 102 cm in men and WC > 88 cm in women) only in men. The proportion of men and women with hypercholesterolemia, diabetes, and low high‐density lipoprotein‐cholesterol plasma concentration remained stable within BMI and WC categories. The proportion of hypertension and smoking in obese men significantly increased from 1995 to 2000. Discussion: The 5‐year increase in BMI and WC is of considerable magnitude in the present population, although several CRFs remained stable within BMI and WC categories.     

Titanium with nanotopography induces osteoblast differentiation through regulation of integrin αV

Topographical modifications of titanium (Ti) at the nanoscale level generate surfaces that regulate several signaling pathways and cellular functions, which may affect the process of osseointegration. Here, we investigated the participation of integrin αV in the osteogenic capacity of Ti with nanotopography. Machined titanium discs (untreated) were submitted to treatment with H₂SO₄/H₂O₂ to produce the nanotopography (nanostructured). First, the greater osteogenic capacity of the nanotopography that increased osteoblast differentiation of mesenchymal stem cells compared with untreated topography was shown. Also, the nanostructured surface increased (regulation ≥ 1.9-fold) the gene expression of 6 integrins from a custom array plate utilized to evaluate the gene expression of 84 genes correlated with cell adhesion signaling pathway, including integrin αV, which is involved in osteoblast differentiation. By silencing integrin αV in MC3T3-E1 cells cultured on nanotopography, the impairment of osteoblast differentiation induced by this surface was observed. In conclusion, it was shown that nanotopography regulates the expression of several components of the cell adhesion signaling pathway and its higher osteogenic potential is, at least in part, due to its ability to upregulate the expression of integrin αV. Together with previous data that showed the participation of integrins α1, β1, and β3 in the nanotopography osseoinduction activity, we have uncovered the pivotal role of this family of membrane receptors in the osteogenic potential of this surface.     

Paraoxonase1-192 polymorphism modulates the effects of regular and acute exercise on paraoxonase1 activity

Regular exercise practise is a protective factor against coronary heart disease and enhances antioxidant systems, whereas acute exercise appears to be a major source of increased oxidative stress. Paraoxonase1 (PON1) is an antioxidant HDL-linked enzyme, whose activity toward paraoxon (PON1 activity) is strongly modulated by the PON1-192 polymorphism, comprising Q and R alleles for low and high PON1 activity, respectively. Another polymorphism at the PON1 locus, the PON1-55, modulates PON1 protein and activity levels. PON1 activity, lipid levels, and oxidized LDL concentration were determined in 17 healthy young volunteers before and after a 16-weeks aerobic exercise training period. Furthermore, PON1 activity was analyzed after a bout of exercise in both situations. We found that regular exercise was associated with a decrease in oxidized LDL levels, and an increase in PON1 activity in QQ subjects and with a decrease in PON1 activity in R carriers. A bout of exercise produced an increase in PON1 activity just after the bout of exercise, followed by a decrease in its activity. A recovery of the basal PON1 activity levels at 24 h was found in QQ subjects regardless of their training status and in trained R carriers, but not in untrained R carriers. These results suggest that the effects of regular and acute exercise on PON1 activity levels are modulated by PON1-192 polymorphism. Changes were less evident for the PON1-55 polymorphism.     

Effect of dolomite on the repair of bone defects in rats: histological study

The aim of the present study was to evaluate histologically and radiographically the tissue response to dolomite [CaMg(CO3)2] and its osteogenic potential in the repair of bone cavities in the calvaria of rats. A bone defect 10 mm in diameter and 1 mm deep was made in the calvaria of male Wistar rats. The defects were filled with dolomite, inorganic bovine bone (positive control), or coagulum (negative control). The animals were euthanized 7, 15, 30, and 60 days after surgery, and specimens were collected for radiographic and microscopic analyses. The bone defects were processed for paraffin embedding and H&E staining. The histological study revealed that dolomite stimulated a moderate inflammatory response, with programmed cell death in the first 15 days, compared to bovine bone which showed a moderate to intense acute response. In the chronic phase, the inflammatory response was characterized by the occurrence of macrophages organized as epithelioid cells in the dolomite group, and giant cells in the bovine-bone group. Fibrosis developed in all three groups; however, encapsulation of the fragments, reabsorption, and osteoconductive activity occurred only in the defects filled with bovine bone. The radiographic analysis showed that the bovine bone was most efficient in the repair of the defects, followed by the dolomite and the coagulum. This study demonstrated that the dolomite stimulated a moderate acute inflammatory response with programmed cell death, and a chronic inflammatory response by means of the phagocytic mononuclear system. Although osteo-conductive activity was not shown, the dolomite favored the repair process, compared to the coagulum group.     

Life history and the evolution of family living in birds

The reason why some bird species live in family groups is an important question of evolutionary biology that remains unanswered. Families arise when young delay the onset of independent reproduction and remain with their parents beyond independence. Explanations for why individuals forgo independent reproduction have hitherto focused on dispersal constraints, such as the absence of high-quality breeding openings. However, while constraints successfully explain within-population dispersal decisions, they fail as an ultimate explanation for variation in family formation across species. Most family-living species are long-lived and recent life-history studies demonstrated that a delayed onset of reproduction can be adaptive in long-lived species. Hence, delayed dispersal and reproduction might be an adaptive life-history decision rather than 'the best of a bad job'. Here, we attempt to provide a predictive framework for the evolution of families by integrating life-history theory into family formation theory. We suggest that longevity favours a delayed onset of reproduction and gives parents the opportunity of a prolonged investment in offspring, an option which is not available for short-lived species. Yet, parents should only prolong their investment in offspring if this increases offspring survival and outweighs the fitness cost that parents incur, which is only possible under ecological conditions, such as a predictable access to resources. We therefore propose that both life-history and ecological factors play a role in determining the evolution of family living across species, yet we suggest different mechanisms than those proposed by previous models.