An Hcp100 gene fragment reveals Histoplasma capsulatum presence in lungs of Tadarida brasiliensis migratory bats.

Histoplasma capsulatum was sampled in lungs from 87 migratory Tadarida brasiliensis bats captured in Mexico (n=66) and Argentina (n=21). The fungus was screened by nested-PCR using a sensitive and specific Hcp100 gene fragment. This molecular marker was detected in 81·6% [95% confidence interval (CI) 73·4-89·7] of all bats, representing 71 amplified bat lung DNA samples. Data showed a T. brasiliensis infection rate of 78·8% (95% CI 68·9-88·7) in bats captured in Mexico and of 90·4% (95% CI 75·2-100) in those captured in Argentina. Similarity with the H. capsulatum sequence of a reference strain (G-217B) was observed in 71 Hcp100 sequences, which supports the fungal findings. Based on the neighbour-joining and maximum parsimony Hcp100 sequence analyses, a high level of similarity was found in most Mexican and all Argentinean bat lung samples. Despite the fact that 81·6% of the infections were molecularly evidenced, only three H. capsulatum isolates were cultured from all samples tested, suggesting a low fungal burden in lung tissues that did not favour fungal isolation. This study also highlighted the importance of using different tools for the understanding of histoplasmosis epidemiology, since it supports the presence of H. capsulatum in T. brasiliensis migratory bats from Mexico and Argentina, thus contributing new evidence to the knowledge of the environmental distribution of this fungus in the Americas.

Pneumocystis diversity as a phylogeographic tool.

Parasites are increasingly used to complement the evolutionary and ecological adaptation history of their hosts. Pneumocystis pathogenic fungi, which are transmitted from host-to-host via an airborne route, have been shown to constitute genuine host markers of evolution. These parasites can also provide valuable information about their host ecology. Here, we suggest that parasites can be used as phylogeographic markers to understand the geographical distribution of intra-specific host genetic variants. To test our hypothesis, we characterised Pneumocystis isolates from wild bats living in different areas. Bats comprise a wide variety of species; some of them are able to migrate. Thus, bat chorology and migration behaviour can be approached using Pneumocystis as phylogeographic markers. In the present work, we find that the genetic polymorphisms of bat-derived Pneumocystis are structured by host chorology. Therefore, Pneumocystis intra-specific genetic diversity may constitute a useful and relevant phylogeographic tool.

Pneumocystis diversity as a phylogeographic tool

Parasites are increasingly used to complement the evolutionary and ecological adaptation history of their hosts. Pneumocystis pathogenic fungi, which are transmitted from host-to-host via an airborne route, have been shown to constitute genuine host markers of evolution. These parasites can also provide valuable information about their host ecology. Here, we suggest that parasites can be used as phylogeographic markers to understand the geographical distribution of intra-specific host genetic variants. To test our hypothesis, we characterised Pneumocystis isolates from wild bats living in different areas. Bats comprise a wide variety of species; some of them are able to migrate. Thus, bat chorology and migration behaviour can be approached using Pneumocystis as phylogeographic markers. In the present work, we find that the genetic polymorphisms of bat-derived Pneumocystis are structured by host chorology. Therefore, Pneumocystis intra-specific genetic diversity may constitute a useful and relevant phylogeographic tool.

Microarchitecture and innervation of the human latissimus dorsi muscle.

Re-investigation of the adult human latissimus dorsi muscle (HLD) by microdissection of acetylcholinesterase (AChE)-stained material revealed a complicated microstructure of this muscle. Motor endplates distribute over the entire muscle; numerous AChE-stained myomyonal and myotendinous junctions are interspersed. After teasing muscle fascicles from selected representative areas, the following results were obtained. Most of the single muscle fibers constituting the fascicles are shorter than the length of the fascicles. They are linked together by myomyonal junctions or by myotendinous intersections end-to-end, end-to-side, or via muscular crossbridges side-to-side, thus forming chains and nets of varying appearance and length. Additionally, many fiber furcations were found. These observations throw light on the microarchitectural basis of local mass changes of the triangular HLD occurring during its convergence from its wide lumbar and thoracic attachment line to its narrow tendon attached to the humeral crista tuberculi minoris. The microstructural observations also explain why motor endplates spread over the whole muscle, instead of being restricted to a single central endplate-band, as is found in the majority of other muscles. To clarify postnatal development, the topography of endplates in adult muscles was compared with fetal and infantile muscles. Primarily, the endplate bands were clearly demarcated; their width then broadened, and they gradually scattered into groups of single endplates. Simultaneous with these developmental changes, a corresponding branching of the thoracodorsal nerve occurs.