Cristina Rodríguez

Frequency of vacA, cagA and babA2 virulence markers in Helicobacter pylori strains isolated from Mexican patients with chronic gastritis

BackgroundHelicobacter pylori has been strongly associated with chronic gastritis, peptic and duodenal ulcers, and it is a risk factor for gastric cancer. Three major virulence factors of H. pylori have been described: the vacuolating toxin (VacA), the cytotoxin-associated gene product (CagA) and the adhesion protein BabA2. Since considerable geographic diversity in the prevalence of H. pylori virulence factors has been reported, the aim of this work was to establish the H. pylori and vacA, cagA and babA2 gene status in 238 adult patients, from a marginal urban area of Mexico, with chronic gastritis.MethodsH. pylori was identified in cultures of gastric biopsies by nested PCR. vacA and cagA genes were detected by multiplex PCR, whereas babA2 gene was identified by conventional PCR.ResultsH. pylori-positive biopsies were 143 (60.1%). All H. pylori strains were vacA+; 39.2% were cagA+; 13.3% were cagA+babA2+ and 8.4% were babA2+. Mexican strains examined possessed the vacA s1, m1 (43.4%), s1, m2 (24.5%), s2, m1 (20.3%) and s2, m2 (11.9%) genotypes.ConclusionThese results show that the Mexican patients suffering chronic gastritis we have studied had a high incidence of infection by H. pylori. Forty four percent (63/143) of the H. pylori strains analyzed in this work may be considered as highly virulent since they possessed two or three of the virulence markers analyzed: vacA s1 cagA babA2 (9.8%, 14/143), vacA s1 babA2 (4.9%, 7/143), and vacA s1 cagA (29.4%, 42/143). However, a statistically significant correlation was not observed between vacAs1, cagA and babA2 virulence markers (χ2 test; P > 0.05).

Better stay together: pair bond duration increases individual fitness independent of age-related variation

Prolonged pair bonds have the potential to improve reproductive performance of socially monogamous animals by increasing pair familiarity and enhancing coordination and cooperation between pair members. However, this has proved very difficult to test robustly because of important confounds such as age and reproductive experience. Here, we address limitations of previous studies and provide a rigorous test of the mate familiarity effect in the socially monogamous blue-footed booby, Sula nebouxii, a long-lived marine bird with a high divorce rate. Taking advantage of a natural disassociation between age and pair bond duration in this species, and applying a novel analytical approach to a 24 year database, we found that those pairs which have been together for longer establish their clutches five weeks earlier in the season, hatch more of their eggs and produce 35% more fledglings, regardless of age and reproductive experience. Our results demonstrate that pair bond duration increases individual fitness and further suggest that synergistic effects between a male and females behaviour are likely to be involved in generating a mate familiarity effect. These findings help to explain the age- and experience-independent benefits of remating and their role in life-history evolution.

El Niño in the Warm Tropics: local sea temperature predicts breeding parameters and growth of blue‐footed boobies

1. There is increasing interest in the impacts of El Niño Southern Oscillation (ENSO) on reproduction of apical predators such as seabirds and marine mammals. Long-term studies documenting ENSO effects on reproduction of seabirds in the warm tropics are scarce, and differential sensitivity of breeding parameters to ENSO has rarely been explored. 2. Analysis of 18 years of breeding data from a colony of the blue-footed booby Sula nebouxii (Milne-Edwards) showed a delay in onset of breeding when the global Southern Oscillation Index was negative; each unit of the atmospheric pressure differential (hPa) across the Pacific Ocean meant a delay of 7 days. 3. ENSO conditions also produced declines in breeding participation, clutch size, brood size, hatching success and fledging success, especially when surface waters surrounding the colony were warmer during winter and spring. Each additional degree (°C) of water temperature produced a reduction of 0.45 fledglings per nest. Different breeding parameters were sensitive to ENSO indices in different blocks of months. 4. Warming of local waters during the winter was associated with decline in ocean productivity in the current year and the following year, consistent with ENSO impacts on breeding parameters being mediated by effects on local productivity and prey availability. However, there was no evidence of lagged effects of ENSO on any breeding parameter. 5. Comparison of 5 years revealed that when local surface waters were warm, chicks grew more slowly, but no effects of ENSO on weight and size of eggs were evident in data of 9 and 7 years, respectively. 6. Our findings extend evidence of impacts of ENSO on seabird reproduction to the eastern tropical Pacific and indicate that several breeding parameters of blue-footed boobies (but not egg size) are affected in the short term by ENSO conditions, particularly by local anomalies in sea surface temperature associated with decline in ocean productivity.

Natural ‘poor start’ does not increase mortality over the lifetime

Poor nutrition and other challenges during infancy can impose delayed costs, and it has been proposed that expression of costs during adulthood should involve increased mortality rather than reduced reproduction. Demonstrations of delayed costs come mostly from experimental manipulations of the diet and hormones of captive infants of short-lived species, and we know very little about how natural poor starts in life affect wild animals over their lifetimes. In the blue-footed booby, sibling conflict obliges younger brood members to grow up suffering aggressive subordination, food deprivation and elevated stress hormone, but surviving fledglings showed no deficit in reproduction over the first 5–10 years. A study of 7927 individuals from two-fledgling and singleton broods from 20 cohorts found no significant evidence of a higher rate of mortality nor a lower rate of recruitment in younger fledglings than in elder fledglings or singletons at any age over the 20 year lifespan. Development of boobies may be buffered against the three challenges of subordination. Experimental challenges to neonates that result in delayed costs have usually been more severe, more prolonged and more abruptly suspended, and it is unclear which natural situations they mimic.

Habitat structure and colony structure constrain extrapair paternity in a colonial bird

Individual variation in sexual fidelity and extrapair paternity (EPP) is widely attributed to environmental heterogeneity, but the only variables known to be influential are food abundance and density of conspecific breeders (potential extrapair partners). Habitat structure is thought to impact EPP but is rarely measured and, when considered, is usually confounded with food abundance and predation pressure. To sidestep these confounds, we tested whether EPP is associated with habitat structure variables and with local conspecific density in a species whose nesting habitat is not used for feeding and lacks predators. In a blue-footed booby, Sula nebouxii, colony, the probability of EPP in a females nest was highest in parts of the study plot where there were few obstacles to locomotion, and was quadratically related to local density of sexually active males, even though local males did not sire the EP chicks. The probability of a male breeder siring EP (extrapair) chicks elsewhere was quadratically related to local density of sexually active males around his nest. From these patterns we infer that both sexes may foray for EP interactions, that males and females nesting at intermediate density are most likely to be accessed by forayers, and that obstacles in the vicinity of a females nest constrain access of foraying males. To our knowledge, this is the first demonstration that individual variation in EPP is associated with habitat structure in the absence of confounding variation in food availability, predation pressure or breeder quality, and the first evidence that EPP opportunities of female and male breeders are reduced by high

Behavioural roles in booby mate switching

The behaviour that mediates divorce and partner change in socially monogamous species is largely unstudied and unknown, although roles and adaptive functions in some birds have been inferred from breeding outcomes, partial behavioural records and captive studies. Here, roles and functions of natural within-season mate switching of a colonial bird were characterized by describing interactions over many days during the whole daylight period. Switching occurred in 5.9% of bluefooted booby pairs and was initiated by desertion of males or, less commonly, females. Three male desertions were consistent with either the Errors of Mate Choice or Incompatibility hypotheses but were better explained by our new Unfaithful Mate hypothesis because infidelity of the mate preceded desertion. Another two male desertions were more consistent with the Better Options hypothesis because the males switched to their ongoing extra-pair (EP) partners. One female desertion was consistent with the Errors of Mate choice or Incompatibility hypotheses, and another with the Better Options hypothesis. All five deserted females switched promptly to their EP partners. Thus, most switches consisted of (1) males replacing a possibly unsatisfactory partner with an ew (already identif ied or to be identif ied) partner, or (2) deserted females pairing with their EP partners.

Behaviorally Induced Camouflage: A New Mechanism of Avian Egg Protection

When animals potentially occupy diverse microhabitats, how can camouflage be achieved? Here we combine descriptive and experimental methods to uncover a novel form of phenotypic plasticity in the camouflage of bird eggs that may be present in other avian taxa. Soil from the bare substrate adheres to the blue-footed booby’s (Sula nebouxii’s) pale eggs, which parents manipulate both under and on top of their webs. Analysis of digital images confirmed that dirtiness increases progressively during the first 16 days of the incubation period, making eggs more similar to the nest substrate. Observations of 3,668 single-egg clutches showed that the probability of egg loss declines progressively over the same time frame and then remains low for the rest of the 41-day incubation period. An experiment showed that when chicken eggs are soiled and exposed in artificial booby nests, they are less likely to be taken by Heermann’s gulls (Larus heermanni) than clean eggs.

Viability of Booby Offspring is Maximized by Having One Young Parent and One Old Parent

It is widely expected that the quality of offspring will vary with the age of their parents and that this variation should influence animals’ choice of mates. However, theoretical predictions for age effects are contradictory and, to our knowledge, we do not know for any wild animal how the quality of offspring is affected by both parents’ ages across their lifespans, or whether mothers’ and fathers’ ages interact. We tackled this question using long-term data on a highly philopatric, insular population of the blue-footed booby (Sula nebouxii). In this species extra-pair paternity is most common in pairs of two young parents or two old parents, implying that these age combinations might prejudice offspring quality. Analysis of the viability of 3,361 offspring of parents up to 21 years old revealed that fledglings with two young parents or two old parents were least likely to become breeders, whereas fledglings with one young parent and one old parent were most likely to do so. For young parents of either sex, offspring viability increased with age of the other parent; for very old parents, it decreased. These effects could be mediated by parents flexibly modifying their investment in offspring in response to their own and their partners´ ages, but evidence for this was lacking. In 5,343 breeding attempts, although mothers’ and fathers’ ages independently affected four heavily care-dependent breeding traits at the clutch and nestling stages, their interaction did not affect any trait. The effects of parental age combinations on viability could also be mediated by genes: fledglings with one young parent and one old parent could benefit from greater heterozygosity or better genes.

Fingerprint Analysis and Identification of Strains ST309 as a Potential High Risk Clone in a Pseudomonas aeruginosa Population Isolated from Children with Bacteremia in Mexico City

Pseudomonas aeruginosa is an opportunistic pathogen and is associated with nosocomial infections. Its ability to thrive in a broad range of environments is due to a large and diverse genome of which its accessory genome is part. The objective of this study was to characterize P. aeruginosa strains isolated from children who developed bacteremia, using pulse-field gel electrophoresis, and in terms of its genomic islands, virulence genes, multilocus sequence type, and antimicrobial susceptibility. Our results showed that P. aeruginosa strains presented the seven virulence genes: toxA, lasB, lecA, algR, plcH, phzA1, and toxR, a type IV pilin alleles (TFP) group I or II. Additionally, we detected a novel pilin and accessory gene, expanding the number of TFP alleles to group VI. All strains presented the PAPI-2 Island and the majority were exoU+ and exoS+ genotype. Ten percent of the strains were multi-drug resistant phenotype, 18% extensively drug-resistant, 68% moderately resistant and only 3% were susceptible to all the antimicrobial tested. The most prevalent acquired β-Lactamase was KPC. We identified a group of ST309 strains, as a potential high risk clone. Our finding also showed that the strains isolated from patients with bacteremia have important virulence factors involved in colonization and dissemination as: a TFP group I or II; the presence of the exoU gene within the PAPI-2 island and the presence of the exoS gene.

No reduction in aggression after loss of a broodmate: a test of the brood size hypothesis

In some vertebrate species, parents create a large brood or litter then, in the event of unfavourable ecological conditions, apparently allow the number of offspring to be adaptively reduced through siblicide. But how is sibling aggression regulated so that deaths occur only in unfavourable conditions? One proposed mechanism is brood size-dependent aggression. Two experiments tested for this mechanism by reducing three-chick broods of blue-footed boobies either during or after the period of dominance hierarchy establishment. In neither experiment did aggression of the two eldest and highest ranking chicks decline after removal of the youngest broodmate, in comparison with controls. These results suggest that dominant booby chicks do not become less aggressive to each other after disappearance of their youngest broodmate and that this species does not show brood size dependent aggression. Elder blue-footed booby chicks increase their attacks on broodmates when they receive less food, and this mechanism may be sufficient to tailor brood size to food availability.