Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N- glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.      

Vegetal cover estimated by digital photographs related to biomass in a grassland site in northern Mexico

A regression model was used to determine the relationship between aerial herbaceous biomass and vegetation coverage estimated by digital images. Four samplings (n=36 each date) of vegetation cover and herbaceous biomass were performed during the growing season in 2011 in a grassland dominated by Bouteloua gracilis in La Cieneguilla, Municipality of Villa Hidalgo, Durango. Average production of dry biomass was 37.36 ± 9.66 g/m², and mean vegetation cover 30.02%. Dry biomass data were tested for normality using the test of Kolmogorov Smirnov, finding a lack of fit. The data were subjected to a logarithmic transformation and the model Ln(y) = 1.637926 + 0.08501X - 0.000586X² with an adjusted R² = 0.89 was found. In order to validate this model, another five samplings were carried out in 2013 at the same site during summer and autumn, using the same sampling size for each date as in 2011. Data collected in 2013 were analyzed with the model Ln (y) = β₀ + β₁X + β₂X². A comparison of regression coefficients was carried out between the 2011 and 2013 models with t (180+144-9-11-2=302, p<0.05) = 1.967. The results indicated that it is possible to use the 2011 regression model to estimate herbaceous aerial biomass from vegetation cover measurements with aerial photographs in La Cieneguilla site during summer and fall.     

Duplicate gene evolution and expression in the wake of vertebrate allopolyploidization

Background  

The mechanism by which duplicate genes originate – whether by duplication of a whole genome or of a genomic segment – influences their genetic fates. To study events that trigger duplicate gene persistence after whole genome duplication in vertebrates, we have analyzed molecular evolution and expression of hundreds of persistent duplicate gene pairs in allopolyploid clawed frogs (Xenopus and Silurana). We collected comparative data that allowed us to tease apart the molecular events that occurred soon after duplication from those that occurred later on. We also quantified expression profile divergence of hundreds of paralogs during development and in different tissues.     

Sexual selection,germline mutation rate and sperm competition

Background  

An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1) Increased sperm production associated with sperm competition may increase mutation rate. (2) Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection.     

Inhibition of host-seeking response and olfactory responsiveness in Anopheles gambiae following blood feeding

The effect of a single blood meal on the host-seeking response of Anopheles gambiae was investigated in the laboratory using a behavioural bioassay, whereas possible changes at the chemosensory level were monitored using electroantennogram recording (EAG). To avoid the possible confounding effect of body size, mosquitoes of a large size class only were used. Five-day old female mosquitoes were given a blood meal on a human arm and exposed to the emanations of a human hand in an olfactometer at 3, 24, 40, 48 and 72 h following the meal and their behaviour and EAG response to host stimuli were compared with that of unfed mosquitoes (controls) of corresponding age. During egg development, mosquitoes had access to glucose and an oviposition tray. The ovarian development of blood-fed mosquitoes that responded to host odours was compared with that of blood-fed mosquitoes that had not been exposed to host odours. The EAG response of blood-fed and control mosquitoes to host odour was examined upon stimulation with air led over incubated human sweat, hexanoic acid, indole and geranyl acetone. EAGs were recorded at times after a blood meal corresponding with those used in the behavioural experiment. There was no host-seeking response at 3 and 24 h post blood meal (pbm). Seven percent of the mosquitoes responded to human emanations 40-h pbm, 27% at 48 h and 68% at 72 h following a blood meal. The average response of controls to host stimuli varied from 35 (at t=40 h) to 67%. There was no ovarian development in the unfed group of mosquitoes. Of the mosquitoes that responded to host odour 48 h pbm, 12.5% (n=5) had ovaries in Christophers' stage IV and the remainder in stage V. Of the mosquitoes that responded 72 h pbm, 66.7% (n=94) had ovaries in stage V and 31.2% (n=44) had recently oviposited. Maximum EAG amplitudes recorded from blood-fed and control mosquitoes were similar for mosquitoes in Christophers' stages I-III, whereas in stage IV EAG amplitudes recorded from the blood-fed group were significantly lower than those of the corresponding control group in response to headspace of incubated human sweat and to indole. The results show that there was a strong inhibition of host seeking in An. gambiae for a period of at least 40 h following a blood meal. Host-seeking returned to pre-blood meal levels 72-h post feeding and was associated with egg maturation. The inhibition of host-seeking behaviour was accompanied by an inhibition of olfactory sensitivity to headspace of incubated sweat and indole just before the resumption of the host-seeking response. The implications of these findings for mosquito surveillance with host odours are discussed.