Optical characterization of DNA origami-shaped silver nanoparticles created through biotemplated lithography.

Here, we study optically resonant substrates fabricated using the previously reported BLIN (biotemplated lithography of inorganic nanostructures) technique with single triangle and bowtie DNA origami as templates. We present the first optical characterization of BLIN-fabricated origami-shaped silver nanoparticle patterns on glass surfaces, comprising optical transmission measurements and surface-enhanced Raman spectroscopy. The formed nanoparticle patterns are examined by optical transmission measurements and used for surface enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) dye molecules. Polarization-resolved simulations reveal that the higher SERS enhancement observed for the bowties is primarily due to spectral overlap of the optical resonances with the Raman transitions of R6G. The results manifest the applicability of the BLIN method and substantiate its potential in parallel and high-throughput substrate manufacturing with engineered optical properties. While the results demonstrate the crucial role of the formed nanogaps for SERS, the DNA origami may enable even more complex nanopatterns for various optical applications.

Life history shifts in an exploited African fish following invasion by a castrating parasite.

Evolutionary theory predicts that infection by a parasite that reduces future host survival or fecundity should select for increased investment in current reproduction. In this study, we use the cestode Ligula intestinalis and its intermediate fish host Engraulicypris sardella in Wissman Bay, Lake Nyasa (Tanzania), as a model system. Using data about infection of E. sardella fish hosts by L. intestinalis collected for a period of 10 years, we explored whether parasite infection affects the fecundity of the fish host E. sardella, and whether host reproductive investment has increased at the expense of somatic growth. We found that L. intestinalis had a strong negative effect on the fecundity of its intermediate fish host. For the noninfected fish, we observed an increase in relative gonadal weight at maturity over the study period, while size at maturity decreased. These findings suggest that the life history of E. sardella has been shifting toward earlier reproduction. Further studies are warranted to assess whether these changes reflect plastic or evolutionary responses. We also discuss the interaction between parasite and fishery-mediated selection as a possible explanation for the decline of E. sardella stock in the lake.

The status and health burden of neurocysticercosis in Mbulu district, northern Tanzania.

OBJECTIVE: The objective of this study was to assess the extent and health burden of neurocysticercosis in the general community of the Mbulu district, northern Tanzania. About 1051 randomly select participants were screened for human cysticercosis. The Cysticercus Western Blot IgG and Computed Tomography scan were used to detect infection by cysticerci. The DALYs was used to assess the community's health burden vis-a-vis neurocysticercosis. RESULTS: The sero-prevalence of HCC was 16.27%. About 76% of 25 selected human cysticercosis sero-positives had neurocysticercosis suggestive lesions on CT scan and 74% had history of epilepsy. Epilepsy caused 2.8 years of life lost and 2.2 healthy years of life lost due to disability per 1000 person-years in Mbulu. The average DALYs imposed due to neurocysticercosis and epilepsy were 3.0 and 3.9 per 1000 person-years, respectively. Neurocysticercosis is a serious public health concern in northern Tanzania.

The risk factors for human cysticercosis in Mbulu District, Tanzania.

The objective of this study was to explore the reasons for the persistence of human cysticercosis (HCC) transmission in Mbulu District, northern Tanzania. The study was carried out in 25 villages, whereby five major risks were identified. The risks were indiscriminate defaecation and improper use of toilets; a free-range system of keeping pigs; indiscriminate or unregulated slaughtering and inadequate meat hygiene and inspection; consumption of undercooked and porcine cysticerci infected pork; and social structure and roles. All of the identified risks were backed up by the immanent lifestyles of the community involved. These findings are important for the development of intervention strategies in the study area.