Mercury Concentration in Breast Milk and Infant Exposure Assessment During the First 90 Days of Lactation in a Midwestern Region of Brazil

Breast milk samples collected from 18 nursing mothers between the 15th and 90th day of lactation were digested in nitric acid in a microwave, and total mercury (THg) levels were quantified by atomic fluorescence spectrometry. Participants responded to a 24-h dietary recall questionnaire on the 74th and 76th day of lactation and to a Food Frequency Questionnaire querying the frequency of fish intake over the last 90 days. Usual intake was estimated using the PC-SIDE software package. A meal of fish was offered on the 75th day of lactation. Mothers’ individual mean THg levels ranged from <0.76 to 22.7 ng/mL during the period, and the mean level for all samples (n?=?142) was 6.47?±6.04 ng/mL. The multilevel mixed linear model used showed high heterogeneity of the mercury levels among the mothers, and THg levels did not change significantly over the period under study. However, a significant increase in THg levels was observed after the intervention with the fish meal. Exposure increased for most infants on the 90th day of lactation, with intakes exceeding the THg provisional tolerable weekly intake (PTWI) at least once during the period for 77.8 % of samples. Mothers consumed mostly food from the fat and grain groups, and a significant correlation was detected between consumption of food of these groups and breast milk THg levels (p?=?0.006 and 0.007). A significant correlation was also found between vegetable consumption and carbohydrate intake and THg levels in the samples (p?=?0.015 and 0.045, respectively). No correlation was found between mothers’ daily fish consumption frequency and THg levels. Although this study showed that mercury intake by infants during lactation may exceed the toxicologically safe exposure level (PTWI), we nevertheless believe that the benefits of lactation for both the mother and the infant outweigh the eventual risks that this exposure may represent.     

Specific Midgut Region Controlling the Symbiont Population in an Insect-Microbe Gut Symbiotic Association

Many insects possess symbiotic bacteria that affect the biology of the host. The level of the symbiont population in the host is a pivotal factor that modulates the biological outcome of the symbiotic association. Hence, the symbiont population should be maintained at a proper level by the host''s control mechanisms. Several mechanisms for controlling intracellular symbionts of insects have been reported, while mechanisms for controlling extracellular gut symbionts of insects are poorly understood. The bean bug Riptortus pedestris harbors a betaproteobacterial extracellular symbiont of the genus Burkholderia in the midgut symbiotic organ designated the M4 region. We found that the M4B region, which is directly connected to the M4 region, also harbors Burkholderia symbiont cells, but the symbionts therein are mostly dead. A series of experiments demonstrated that the M4B region exhibits antimicrobial activity, and the antimicrobial activity is specifically potent against the Burkholderia symbiont but not the cultured Burkholderia and other bacteria. The antimicrobial activity of the M4B region was detected in symbiotic host insects, reaching its highest point at the fifth instar, but not in aposymbiotic host insects, which suggests the possibility of symbiont-mediated induction of the antimicrobial activity. This antimicrobial activity was not associated with upregulation of antimicrobial peptides of the host. Based on these results, we propose that the M4B region is a specialized gut region of R. pedestris that plays a critical role in controlling the population of the Burkholderia gut symbiont. The molecular basis of the antimicrobial activity is of great interest and deserves future study.     

Infection-Mediated Priming of Phagocytes Protects against Lethal Secondary Aspergillus fumigatus Challenge

Phagocytes restrict the germination of Aspergillus fumigatus conidia and prevent the establishment of invasive pulmonary aspergillosis in immunecompetent mice. Here we report that immunecompetent mice recovering from a primary A. fumigatus challenge are protected against a secondary lethal challenge. Using RAGγc knock-out mice we show that this protection is independent of T, B and NK cells. In protected mice, lung phagocytes are recruited more rapidly and are more efficient in conidial phagocytosis and killing. Protection was also associated with an enhanced expression of CXCR2 and Dectin-1 on bone marrow phagocytes. We also show that protective lung cytokine and chemokine responses are induced more rapidly and with enhanced dynamics in protected mice. Our findings support the hypothesis that following a first encounter with a non-lethal dose of A. fumigatus conidia, the innate immune system is primed and can mediate protection against a secondary lethal infection.     

Recovery of tree and mammal communities during large‐scale forest regeneration in Kibale National Park,Uganda

Tropical landscapes are changing rapidly as a result of human modifications; however, despite increasing deforestation, human population growth, and the need for more agricultural land, deforestation rates have exceeded the rate at which land is converted to cropland or pasture. For deforested lands to have conservation value requires an understanding of regeneration rates of vegetation, the rates at which animals colonize and grow in regenerating areas, and the nature of interactions between plants and animals in the specific region. Here, we present data on forest regeneration and animal abundance at four regenerating sites that had reached the stage of closed canopy forest where the average dbh of the trees was 17 cm. Overall, 20.3 percent of stems were wind‐dispersed species and 79.7 percent were animal‐dispersed species, while in the old‐growth forest 17.3 percent of the stems were wind‐dispersed species. The regenerating forest supported a substantial primate population and encounter rate (groups per km walked) in the regenerating sites was high compared to the neighboring old‐growth forests. By monitoring elephant tracks for 10 yr, we demonstrated that elephant numbers increased steadily over time, but they increased dramatically since 2004. In general, the richness of the mammal community detected by sight, tracks, feces, and/or camera traps, was high in regenerating forests compared to that documented for the national park. We conclude that in Africa, a continent that has seen dramatic declines in the area of old‐growth forest, there is ample opportunity to reclaim degraded areas and quickly restore substantial animal populations.     

The Influence of Spatial Attributes on Fragment Occupancy and Population Structure in the Mexican Mantled Howler (<Emphasis Type="Italic">Alouatta palliata mexicana</Emphasis>)

It is essential to document habitat occupancy patterns and population structure to facilitate the survival of primates in areas of anthropogenic disturbance. The overlapping of the Nearctic and Neotropical regions in the Olmec region of Mexico make this area particularly important as part of a natural biological corridor that harbors a high number of endemic species and connects the Atlantic and Pacific coastal plains. We surveyed Alouatta palliata mexicana (Mexican mantled howlers) in a 300-km² area to determine if fragment occupation and subpopulation structure were related to the spatial attributes of the fragments. We measured the fragment size and shape as well as the distances to the nearest road, human settlement, agricultural field, and nearest neighboring fragment. During 1 year (ca. 4500 fieldwork hours) we surveyed 48 fragments, 17 of which were occupied, and counted 198 howlers. Larger fragments that were farther from agricultural activities were more likely to be occupied. Subpopulation size and number of individuals in all age–sex classes increased in larger fragments that were closer to other fragments. We found more females and juveniles, as well as more females per male in fragments that were farther from roads and we found fewer immatures per female, females per male, and individuals per area in more irregular fragments. In addition, more males and immatures per female occurred in fragments that were farther from agricultural fields. The Olmec Region is located at the center of the geographic distribution of mantled howlers in Mexico, and could therefore play a fundamental role in maintaining the contact between different populations. However, our study suggests that mantled howlers are highly threatened by anthropogenic habitat disturbance in this area, mainly through the loss of their habitat and contact with humans.     

Natural killer cells promote early CD8 T cell responses against cytomegalovirus

Understanding the mechanisms that help promote protective immune responses to pathogens is a major challenge in biomedical research and an important goal for the design of innovative therapeutic or vaccination strategies. While natural killer (NK) cells can directly contribute to the control of viral replication, whether, and how, they may help orchestrate global antiviral defense is largely unknown. To address this question, we took advantage of the well-defined molecular interactions involved in the recognition of mouse cytomegalovirus (MCMV) by NK cells. By using congenic or mutant mice and wild-type versus genetically engineered viruses, we examined the consequences on antiviral CD8 T cell responses of specific defects in the ability of the NK cells to control MCMV. This system allowed us to demonstrate, to our knowledge for the first time, that NK cells accelerate CD8 T cell responses against a viral infection in vivo. Moreover, we identify the underlying mechanism as the ability of NK cells to limit IFN-alpha/beta production to levels not immunosuppressive to the host. This is achieved through the early control of cytomegalovirus, which dramatically reduces the activation of plasmacytoid dendritic cells (pDCs) for cytokine production, preserves the conventional dendritic cell (cDC) compartment, and accelerates antiviral CD8 T cell responses. Conversely, exogenous IFN-alpha administration in resistant animals ablates cDCs and delays CD8 T cell activation in the face of NK cell control of viral replication. Collectively, our data demonstrate that the ability of NK cells to respond very early to cytomegalovirus infection critically contributes to balance the intensity of other innate immune responses, which dampens early immunopathology and promotes optimal initiation of antiviral CD8 T cell responses. Thus, the extent to which NK cell responses benefit the host goes beyond their direct antiviral effects and extends to the prevention of innate cytokine shock and to the promotion of adaptive immunity.     

Sex differences in leadership during group movement in mantled howler monkeys (Alouatta palliata)

Benefits of group life depend in large part on whether animals remain cohesive, which often requires collective decisions about where and when to move. During a group movement, the leader may be considered as the individual occupying the vanguard position of the group progression, when its movement evokes following by other group members. In nondespotic societies, individuals with greater incentives to move frequently are leaders. During 15 months of observations (1,712 contact hours), we investigated two mantled howler monkey (Alouatta palliata) groups at La Flor de Catemaco (Los Tuxtlas, Mexico) to examine whether sex and female reproductive state influenced leadership likelihood in two contexts: movements toward feeding trees; movements associated with loud calls, a group-defense behavior used by males of this genus. Females led and occupied forward positions during group movements toward feeding trees more often than adult males. Adult females led these movements more frequently when they were gestating than when they were lactating or cycling. There were no differences between sexes in the leadership of group movements associated with loud calls. Leadership by gestating females is perhaps the result of their higher nutritional/energetic needs when compared with cycling females, and of their greater mobility when compared with lactating females carrying dependent offspring. Female leadership during movements toward feeding trees may be a mechanism to optimize access to food resources in mantled howler monkeys.     

Effect of 1,25(OH)2D3 on bone morphogenetic protein-3 mRNA expression

Bone morphogenetic proteins (BMPs) are members to the transforming growth factor-beta superfamily. They induce ectopic bone formation in rat and are pleiotropic initiators of inducible osteogenic precursor cells. A lot of reports have studied the presence of BMPs and their effects on bone marker expression in many different cell lines, however none describe the regulation of BMP3 by different factors and expression conditions. When a human bone marrow stromal cell (HBMSC) culture was treated simultaneously with 1,25(OH)2D3 (10(-8) M) and BMP3 (2.5 ng/ml), the total osteocalcin content in the cell layer and in the culture medium was higher than when the culture was treated with either factor alone (162%). To elucidate this synergistic activity, Northern blot analysis was done to study the effect of 1,25(OH)2D3 on BMP3 mRNA expression. Several human cell lines (MNNG, U-2OS, MG-63, KHOS, TE85, HOS) and HBMSC were treated by 1,25(OH)2D3 (10(-8) M for 24 h). Purified mRNA from treated and untreated cells were denatured using glyoxal and dimethylsulfoxide, and were fractionated on a 1% agarose gel. After electrophoresis, RNA were blotted onto a nylon membrane and incubated with 32P-labeled BMP3 and GAPDH riboprobes. Northern blot analysis revealed that, the BMP3 mRNA level was increased in a few cell lines (MG-63, HBMSC, HOS) after the addition of 1,25(OH)2D3 when compared to the untreated cells (127%+/-1; 130.5%+/-19.5; 207%+/-14). An higher stimulation was observed in HBMSC primary culture when compared to differentiated HBMSC. In view of these results, we now investigate the following hypothesis: does the BMP3 promoter exhibit the vitamin D receptor response like the osteocalcin gene?