Mobilization of HIV Spread by Diaphanous 2 Dependent Filopodia in Infected Dendritic Cells

Paramount to the success of persistent viral infection is the ability of viruses to navigate hostile environments en route to future targets. In response to such obstacles, many viruses have developed the ability of establishing actin rich-membrane bridges to aid in future infections. Herein through dynamic imaging of HIV infected dendritic cells, we have observed how viral high-jacking of the actin/membrane network facilitates one of the most efficient forms of HIV spread. Within infected DC, viral egress is coupled to viral filopodia formation, with more than 90% of filopodia bearing immature HIV on their tips at extensions of 10 to 20 µm. Live imaging showed HIV filopodia routinely pivoting at their base, and projecting HIV virions at µm.sec⁻¹ along repetitive arc trajectories. HIV filopodial dynamics lead to up to 800 DC to CD4 T cell contacts per hour, with selection of T cells culminating in multiple filopodia tethering and converging to envelope the CD4 T-cell membrane with budding HIV particles. Long viral filopodial formation was dependent on the formin diaphanous 2 (Diaph2), and not a dominant Arp2/3 filopodial pathway often associated with pathogenic actin polymerization. Manipulation of HIV Nef reduced HIV transfer 25-fold by reducing viral filopodia frequency, supporting the potency of DC HIV transfer was dependent on viral filopodia abundance. Thus our observations show HIV corrupts DC to CD4 T cell interactions by physically embedding at the leading edge contacts of long DC filopodial networks.     

Creatine kinase-MB isoenzyme adaptations in stressed human skeletal muscle of marathon runners

The creatine kinase (CK) isoenzyme composition was determined in serial gastrocnemius muscle biopsies obtained from 12 male marathon runners. The mean muscle CK-MB composition significantly increased after chronic exercise (training) from 5.3% (pretraining) to 7.7% (premarathon) as well as after acute exercise (postmarathon) to 10.5% of the total CK activity (P less than 0.05). However, no significant differences in total CK activities were detected. Additionally, mitochondrial CK and CK-BB isoenzymes were present in muscle homogenates. A significant correlation was observed in the increase in mean serum total CK (3,322 U/l) and CK-MB (174 U/l) activities 24 h after the race (r = 0.98, P less than 0.05). These results show that gastrocnemius muscle adapts to long-distance training and racing with increased CK-MB activities and imply that skeletal muscle is the major source of elevated serum CK-MB activities in marathon runners.     

Cleavage inhibition in marine eggs by puromycin and 6-dimethylaminopurine

The possibility is discussed that puromycin may not inhibit cleavage in marine eggs solely by inhibiting protein synthesis. It is suggested that part of the effect of puromycin is through 6-dimethylaminopurine (DMAP) (the purine component of puromycin) a potent cleavage inhibitor which appears to enhance protein synthesis in sea urchin eggs.     

Ex situ breeding programs benefit from science-based cooperative management

Science-based management confers a variety of benefits to wildlife populations that are cooperatively managed by zoos and aquariums, including those managed through the Association of Zoos and Aquariums. Briefly, when management strategies are successful, they result in reproductively robust populations that better retain genetic diversity and limit inbreeding than unmanaged populations. Although the benefits of demographic and genetic management have been well documented throughout both the scientific and popular literature, it has also been established that the majority of managed populations in zoos and aquariums are not meeting the minimum criteria believed to convey long-term biological viability. For most of these populations, an inability to meet viability criteria is not an inherent failure of how cooperative management is implemented. Furthermore, in recent years, we have perceived that the need to meet specific viability goals sometimes has obscured the benefits that these populations receive from rigorous, science-based management. To better clarify the conversation surrounding population viability in zoos and aquariums, we seek to decouple viability measures and how they predict population persistence from the benefits conferred to populations through science-based management. A primary goal of population management is to facilitate the persistence of priority species for longer than would be expected if no such management were implemented. Although current viability measures and future projections of viability are important tools for assessing the likelihood of population persistence, they are not indicators of which populations may most benefit from science-based management. Here, we review the history and purpose of applying science-based management to zoo and aquarium populations, describe measures of population viability and caution against confusing those measures of viability with population management goals or long-term population sustainability, and clearly articulate the benefits conferred to zoo and aquarium populations by science-based management.