Heads or tails? Structural events and molecular mechanisms that promote mammalian sperm acrosomal exocytosis and motility

Sperm structure has evolved to be very compact and compartmentalized to enable the motor (the flagellum) to transport the nuclear cargo (the head) to the egg. Furthermore, sperm do not exhibit progressive motility and are not capable of undergoing acrosomal exocytosis immediately following their release into the lumen of the seminiferous tubules, the site of spermatogenesis in the testis. These cells require maturation in the epididymis and female reproductive tract before they become competent for fertilization. Here we review aspects of the structural and molecular mechanisms that promote forward motility, hyperactivated motility, and acrosomal exocytosis. As a result, we favor a model articulated by others that the flagellum senses external signals and communicates with the head by second messengers to affect sperm functions such as acrosomal exocytosis. We hope this conceptual framework will serve to stimulate thinking and experimental investigations concerning the various steps of activating a sperm from a quiescent state to a gamete that is fully competent and committed to fertilization. The three themes of compartmentalization, competence, and commitment are key to an understanding of the molecular mechanisms of sperm activation. Comprehending these processes will have a considerable impact on the management of fertility problems, the development of contraceptive methods, and, potentially, elucidation of analogous processes in other cell systems.Fil: Buffone, Mariano Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina. University of Pennsylvania; Estados UnidosFil: Ijiri, Takashi W.. University of Pennsylvania; Estados UnidosFil: Cao, Wenlei. University of Pennsylvania; Estados UnidosFil: Merdiushev, Tanya. University of Pennsylvania; Estados UnidosFil: Aghajanian, Haig K.. University of Pennsylvania; Estados UnidosFil: Gerton, George L.. University of Pennsylvania; Estados Unido

A Kinematic Approach for Efficient and Robust Simulation of the Cardiac Beating Motion

Computer simulation techniques for cardiac beating motions potentially have many applications and a broad audience. However, most existing methods require enormous computational costs and often show unstable behavior for extreme parameter sets, which interrupts smooth simulation study and make it difficult to apply them to interactive applications. To address this issue, we present an efficient and robust framework for simulating the cardiac beating motion. The global cardiac motion is generated by the accumulation of local myocardial fiber contractions. We compute such local-to-global deformations using a kinematic approach; we divide a heart mesh model into overlapping local regions, contract them independently according to fiber orientation, and compute a global shape that satisfies contracted shapes of all local regions as much as possible. A comparison between our method and a physics-based method showed that our method can generate motion very close to that of a physics-based simulation. Our kinematic method has high controllability; the simulated ventricle-wall-contraction speed can be easily adjusted to that of a real heart by controlling local contraction timing. We demonstrate that our method achieves a highly realistic beating motion of a whole heart in real time on a consumer-level computer. Our method provides an important step to bridge a gap between cardiac simulations and interactive applications

Involvement of 11-ketotestosterone in hooknose formation in male pink salmon (Oncorhynchus gorbuscha) jaws

Mature male Pacific salmon (Oncorhynchus spp.) develop a hooknose, as a secondary male sexual characteristic, during the spawning period. It is likely that androgens regulate hooknose formation. However, endocrinological and histochemical details about the relationship between androgens and hooknose formation are poorly understood. In this study, we performed assays of serum androgens, detection of androgen receptor (AR) in hooknose tissues, external morphological measurement of hooknose-related lengths, and microscopic observation of hooknose tissues of pink salmon (O. gorbuscha) at different stages of sexual maturation. Expression of the ar beta gene was detected in hooknose tissues of males but not females. The elongation of these tissues was mediated directly via androgens. Serum 11-ketotestosterone (11-KT) concentrations indicated a significant positive correlation with both jaw lengths during sexual maturation of males. In the upper jaw, cartilage tissue developed during hooknose formation, and AR-immunoreactive chondrocytes were located in the rostal-vetral regions of hooknose cartilage in maturing male. The chondrocytes in maturing males before entering into rivers exhibited rich cytoplasm with high cell activity than at other sexual development stages. On the other hand, in the lower jaw, the development of the spongiosa-like bone meshworks. AR-immunoreactivity was detected in a proportion of the osteocytes and osteoblast-like cells in the spongiosa-like bone meshworks. These results indicate that hooknose formation in pink salmon, which is associated with the buildup of a structure with sufficient strength that it can be used to attack other males on the spawning ground, is regulated by 11-KT. (C) 2018 Elsevier Inc. All rights reserved

Sequential image completion for high-speed large-pixel number sensing

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