Subnanometer-resolution structures of the grass carp reovirus core and virion.

Grass carp reovirus (GCRV) is a member of the Aquareovirus genus of the family Reoviridae, a large family of double-stranded RNA (dsRNA) viruses infecting plants, insects, fishes and mammals. We report the first subnanometer-resolution three-dimensional structures of both GCRV core and virion by cryoelectron microscopy. These structures have allowed the delineation of interactions among the over 1000 molecules in this enormous macromolecular machine and a detailed comparison with other dsRNA viruses at the secondary-structure level. The GCRV core structure shows that the inner proteins have strong structural similarities with those of orthoreoviruses even at the level of secondary-structure elements, indicating that the structures involved in viral dsRNA interaction and transcription are highly conserved. In contrast, the level of similarity in structures decreases in the proteins situated in the outer layers of the virion. The proteins involved in host recognition and attachment exhibit the least similarities to other members of Reoviridae. Furthermore, in GCRV, the RNA-translocating turrets are in an open state and lack a counterpart for the sigma1 protein situated on top of the close turrets observed in mammalian orthoreovirus. Interestingly, the distribution and the organization of GCRV core proteins resemble those of the cytoplasmic polyhedrosis virus, a cypovirus and the structurally simplest member of the Reoviridae family. Our results suggest that GCRV occupies a unique structure niche between the simpler cypoviruses and the considerably more complex mammalian orthoreovirus, thus providing an important model for understanding the structural and functional conservation and diversity of this enormous family of dsRNA viruses.

Gender differences in life circumstances, monthly income, risky sexual and drug behaviors among injection drug users in Dar es Salaam, Tanzania

This study investigated the gender difference between male and female injection drug users’ (IDUs) life circumstances, income and risky sexual and drug behaviors. The study sample comprised of 318 male and 249 female injection drug users in Dar es Salaam, Tanzania. There were gender differences between male and female IDUs in terms of life circumstances and sexual behaviors. There were no differences in the drug behaviors among the two sexes. Women were more likely to be 21-25 years of age, have had more sexual partners in the last 30 days, traded sex for money, and have been sexually abused as a child. On the other hand, the males were more likely to be 26-30 years of age and have never used a condom during sex in the last 30 days. Regardless of the differences in sexual risk behaviors by gender, both male and female injection drug users in Dar es Salaam are at risk of HIV/AIDS, blood borne and other sexually transmitted diseases associated with drug use.^

Investigating the epidemic of heroin use in Dar es Salaam, Tanzania: Recognizing the issues of heroin smokers

Since heroin was introduced to East Africa during the 1980s, heroin use practices have changed rapidly in response to various internal and external pressures. The aim of this study was to identify and describe the population of heroin users and locations of heroin use in Dar es Salaam, Tanzania, in order to understand recent contexts of heroin use. The study took place between June 30 and August 19, 2011, in all three districts (Kinondoni, Ilala, and Temeke) of Dar es Salaam. We mapped sites using a Global Positioning System device, counted numbers of heroin users, and conducted informal interviews with heroin users. The mixed-methods analyses of the data included quantifying the basic demographic and aggregate information about the sites and heroin users, as well as qualitative analysis and coding of fieldnotes from observations and responses to interviews which was used to identify themes and characteristics of heroin users. ^ We identified a total of 150 sites and counted a total of 1046 male and 46 female non-injecting drug users and 78 male and 9 female injecting drug users (IDUs) of heroin. We found that social organization existed at some of the sites, with 31% (n=47) of sites reporting having a leader and 44% (n=66) of sites reporting mutual aid between users frequenting the site. We had difficulty locating IDUs and female drug users, and the majority of users we encountered were heroin smokers of kokteli, a mixture of heroin, cannabis, and/or tobacco which is smoked like a cigarette. ^ This research highlighted heroin smokers’ desire for access to drug treatment services. The current methadone-based medication assisted treatment (MAT) program is funded and operates as an HIV prevention program for IDUs to reduce HIV infection in this population and slow or stop the spread of a second wave of HIV infection in the general population. However, smokers perceived MAT to be primarily a drug use prevention or cessation program and felt unjustly neglected from the intervention, leading to a tense relationship with IDUs. From a public health standpoint, future interventions should include heroin smokers to prevent HIV transmission. ^

Effects of salinity, temperature and cadmium stress on cadmium -binding protein in the grass shrimp, {\it Palaemonetes pugio}

The combined effects of salinity, temperature and cadmium stress on survival and adaptation through cadmium-binding protein (CdBP) accumulation were studied in the grass shrimp, Palaemonetes pugio. In 96-hour bioassays, shrimp were exposed to zero or one of three levels of cadmium, under one of six different salinity (15, 25, or 35$\perthous$) and temperature (20 or 30$\sp\circ$C) regimes. CdBP concentrations were quantified in survivors from the 24 exposure groups. Salinity and temperature did not affect survivorship unless the shrimp were also exposed to cadmium. Grass shrimp were most sensitive to cadmium at low salinity-high temperature, and least sensitive at high salinity-low temperature. The incidence of cadmium-associated black lesions in gill tissue was influenced by salinity and temperature stress. P. pugio produced a 10,000 dalton metallothionein-like CdBP when exposed to at least 0.1 mg Cd$\sp{2+}$/L for 96 hours. Accumulation of CdBP was increased with increases in the exposure cadmium level, increases in temperature and decreases in salinity, independently and in conjunction with one another. Maximum CdBP concentrations occurred in grass shrimp that survived the salinity-temperature-cadmium conditions creating maximum stress as measured by highest mortality, not necessarily in shrimp exposed to the highest cadmium levels. The potential utility of this method as a monitor of physiological stress in estuarine biota inhabiting metal-polluted environments is discussed. ^