Cytogenetical and histological studies in testis of Tayassu tajacu (Cateto), Tayassu pecari (Queixada) and a natural interspecific hybrid

The karyotype, the histological structure of the testis and the synaptonemal complex (SC) of the mammalian species Tayassu tajacu , Tayassu pecari and of an interspecific male hybrid captured in nature were analysed. The specimens of T. tajacu (2n=30) and T. pecari (2n=26) exhibited seminiferous tubules with germ cells in all spermatogenesis stages. In the SC studies both species had a regular structure, easily identified in the autosomes and in the sex chromosomes. The hybrid (2n=28) had seminiferous tubules with almost all germinal cells in the spermatogonium stage and only a few cells in the primary spermatocyte stage. Gross abnormalities in SC were observed. A few lateral elements showed regular or partially regular synapsis, other lateral elements were synapsed as multivalents, and most axial elements remained unsynapsed. The results suggest that the karyotypes of the parental species have sufficient differentiation to avoid chromosome synapsis. Alternatively, the hypothesis of the existence of genetic incompatibilities between the parental species is discussed.     

Post-mortem findings in 54 cases of anesthetic associated death in cats from two spay-neuter programs in New York State

Anesthetic-associated death (AAD) in cats is infrequent, but occurs far more frequently than in people. Post-mortem investigations of AAD in cats are uncommon, and results only sporadically published. Here we report the findings in 54 cases of AAD in cats. Significant gross and/or microscopic pre-existing disease, including pulmonary, cardiac, and systemic disease, was detected in 33% of cases. Pulmonary disease was most frequently diagnosed (24% of cases), and included cases of Aelurostrongylus abstrusus infection (9% of cases). Heart disease, including two cases of hypertrophic cardiomyopathy, was less frequent (11% of cases). Four percent died from surgical complications. No?significant gross or microscopic disease was detected in 63% of cases. Additional studies are needed to determine if these findings are representative of AAD in cats in other geographic areas or with access to veterinary care. This study demonstrates that post-mortem investigation of AADs is an important and worthwhile endeavor.     

Comment on "Nonreciprocal light propagation in a silicon photonic circuit"

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.     

Impaired respiratory and body temperature control upon acute serotonergic neuron inhibition

Physiological homeostasis is essential for organism survival. Highly responsive neuronal networks are involved, but their constituent neurons are just beginning to be resolved. To query brain serotonergic neurons in homeostasis, we used a neuronal silencing tool, mouse RC::FPDi (based on the synthetic G protein-coupled receptor Di), designed for cell type-specific, ligand-inducible, and reversible suppression of action potential firing. In mice harboring Di-expressing serotonergic neurons, administration of the ligand clozapine-N-oxide (CNO) by systemic injection attenuated the chemoreflex that normally increases respiration in response to tissue carbon dioxide (CO(2)) elevation and acidosis. At the cellular level, CNO suppressed firing rate increases evoked by CO(2) acidosis. Body thermoregulation at room temperature was also disrupted after CNO triggering of Di; core temperatures plummeted, then recovered. This work establishes that serotonergic neurons regulate life-sustaining respiratory and thermoregulatory networks, and demonstrates a noninvasive tool for mapping neuron function.     

Cutaneous sterile pyogranuloma/granuloma syndrome in a dog

A case of canine cutaneous sterile pyogranuloma/granuloma syndrome (SPGS) with generalized asymmetrical alopecia and plaques is described. Results from histopathologic examination were suggestive of SPGS and failed to demonstrate any etiological agent. A systematic approach on how to definitively rule out infectious skin diseases is discussed.