In vivo and in vitro Leishmania amazonensis infection induces autophagy in macrophages

Autophagy is the primary mechanism of degradation of cellular proteins and at least two functions can be attributed to this biological phenomenon: increased nutrient supply via recycling of the products of autophagy under nutrient starvation; and antimicrobial response involved in the innate immune system. Many microorganisms induce host cell autophagy and it has been proposed as a pathway by which parasites compete with the host cell for limited resources. In this report we provide evidence that the intracellular parasite Leishmania amazonensis induces autophagy in macrophages. Using western blotting, the LC3II protein, a marker of autophagosomes, was detected in cell cultures with a high infection index. Macrophages infected with L. amazonensis were examined by transmission electronic microscopy, which revealed enlarged myelin-like structures typical late autophagosome and autolysosome. Other evidence indicating autophagy was Lysotracker red dye uptake by the macrophages. Autophagy also occurs in the leishmaniasis skin lesions of BALB/c mice, detected by immunohistochemistry with anti-LC3II antibody. In this study, autophagy inhibitor 3-methyladenine (3MA) reduced the infection index, while autophagy inductors, such as rapamycin or starvation, did not alter the infection index in cultivated macrophages, suggesting that one aspect of the role of autophagy could be the provision of nutritive support to the parasite.     

Model simulations of gas mixing and ventilation distribution in the human lung

A new lung model that incorporates intra-acinar diffusion- and convection-dependent inhomogeneities (DCDI) and interregional and intraregional convection-dependent inhomogeneities (CDI) is described. The model is divided into two regions, each containing two subunits. Each of the four subunits in the model consists of a multi-branch-point structure, based on the anatomic data from Haefeli-Bleuer and Weibel (Anat. Record 220: 401-414, 1988). The subunit turnover (TO), i.e., the ratio of subunit tidal to resting volume, and the flow sequences (FS) between the subunits are used as model parameters. The model simulates the normalized alveolar slope (Sn), Fowler and Bohr dead space (VDF and VDB), and alveolar mixing efficiency (AME) as a function of breath number (n) during a multiple-breath N2 washout (MBNW). For the first breath of the MBNW, these indexes are poorly sensitive to the TO distribution or FS between the subunits. However, as the washout proceeds, the n dependence of both Sn and VDB becomes markedly distinct for simulations with different TO and FS. VDF increases only slightly with n during the MBNW for a large range of TO and FS combinations, and AME is independent of FS. Comparison of published experimental observations with model simulations gave a consistent picture of ventilation maldistribution in the human lung. MBNW simulations in conditions of weightlessness, which will be performed shortly in Spacelab, suggest that it will be possible to evaluate quantitatively the intraregional elastic inhomogeneities in the human lung.     

Year‐round spatial movements and trophic ecology of Trindade Petrels (Pterodroma arminjoniana)

Trindade Petrels (Pterodroma arminjoniana) are vulnerable gadfly petrels that breed on the remote Trindade Island, located ~1100 km off the Brazilian coast. Little is known about their spatial ecology, and their trophic ecology has only been described for the breeding season. We tagged four Trindade Petrels with global location sensing loggers (GLS) from October 2013 to November 2014 and sampled the blood and feathers (innermost primary and the eighth secondary) of 14 individuals to evaluate their year‐round spatial and isotopic ecology. We examined individual distributions, habitat use and suitability, activity, and isotopic values during the breeding, migration, and non‐breeding periods. Trindade Petrels used areas in the southwest Atlantic Ocean (between 10°N and 50°S in latitude) during the breeding season. They migrated through pelagic waters of the tropical Atlantic to the northwest Atlantic, where they spent the non‐breeding season. Trindade Petrels used mostly tropical to subtropical waters in areas of intermediate to high wind speeds and low marine productivity. Individuals spent more time foraging at night than during the day. During the breeding season, birds in northerly areas had higher carbon‐13 values, and birds that used more pelagic areas foraged on prey at a higher trophic level (higher nitrogen‐15 values) than those in more southern and coastal areas. Isotopic values during the breeding, migration, and non‐breeding periods differed, possibly due to differences among individuals in their at‐sea distribution throughout the year. We confirmed the non‐breeding distribution of Trindade Petrels, which was previously known only from vessel sightings and stranded birds. Our results also suggest a strong temporal segregation in the at‐sea distribution and trophic ecology between two groups of individuals, which might indicate the existence of two separate breeding populations.     

Karyotype of Callithrix mauesi (Callitrichidae,Primates) and its relations with those of C. emiliae and C. jacchus

A study was conducted on the most recently described marmoset species, Callithrix mauesi, and the results obtained were compared to those previously reported for the karyotypes of C. jacchus and C. emiliae. No mechanism of chromosome rearrangement differentiates the karyotypes of C. mauesi (2n = 44) and C. emiliae (2n = 44), which diverge from C. jacchus (2n = 46) by a Robertsonian translocation and a paracentric inversion. C. mauesi, like C. emiliae, presents telomeric constitutive heterochromatin in various chromosomes, forming large heterochromatic blocks in some. This does not occur in C. jacchus, which basically presents centromeric constitutive heterochromatin. The karyotype of C. mauesi differs from that of C. emiliae only by the amount and distribution of this telomeric constitutive heterochromatin. One of the chromosomes presenting a heterochromatic block in C. mauesi is chromosome X, a fact not previously reported in the Order Primates. The present chromosome data show that C. mauesi is closer to C. emiliae than to C. jacchus, in agreement with its inclusion in the C. argentata group. In the present paper, we describe for the first time, at the chromosome level, chimerism between fraternal twins of the same sex (XY/XY), with the heterochromatic block of pair 2 being the marker. © 1994 Wiley-Liss, Inc.