Surveillance of Schistosoma japonicum Infection in Domestic Ruminants in the Dongting Lake Region, Hunan Province, China

Background: Schistosomiasis japonica is prevalent in Asian countries and it remains a major public health problem in China. The major endemic foci are the marsh and lake regions of southern China, particularly the Dongting Lake region bordering Hunan and Hubei provinces, and the Poyang Lake region in Jiangxi province. Domestic ruminants, especially bovines, have long been considered to play a major role in the transmission of Schistosoma japonicum to humans. Methods and Findings: A miracidial hatching technique was used to investigate the prevalence of S. japonicum infections in domestic ruminants and field feces collected from two towns located to the south and east of Dongting Lake, Hunan province, between 2005 and 2010. The overall prevalence of infection was not significantly reduced from 4.93 % in 2005 to 3.64 % in 2008, after which it was maintained at this level. Bovines comprised 23.5–58.2 % of the total infected ruminants, while goats comprised 41.8–76.5%. Infection rates in cattle and goats were significantly higher than those found in buffalo in most study years. The prevalence in buffalo younger than three years was significantly higher than that in those aged over three years. All the positive field samples of feces were derived from bovines in Nandashan. In Matang Town, 61.22 % of the positive field feces were from bovines, while the rest were from goats. The positive rates for field feces were approximately the same in April and November/October. Conclusions: The present study found that bovines and goats are major sources of S. japonicum infection in the Dongtin

Chromosome-level genome assembly and annotation of rare and endangered tropical bivalve, Tridacna crocea

Abstract Tridacna crocea is an ecologically important marine bivalve inhabiting tropical coral reef waters. High quality and available genomic resources will help us understand the population structure and genetic diversity of giant clams. This study reports a high-quality chromosome-scale T. crocea genome sequence of 1.30 Gb, with a scaffold N50 and contig N50 of 56.38 Mb and 1.29 Mb, respectively, which was assembled by combining PacBio long reads and Hi-C sequencing data. Repetitive sequences cover 71.60% of the total length, and a total of 25,440 protein-coding genes were annotated. A total of 1,963 non-coding RNA (ncRNA) were determined in the T. crocea genome, including 62 micro RNA (miRNA), 58 small nuclear RNA (snRNA), 83 ribosomal RNA (rRNA), and 1,760 transfer RNA (tRNA). Phylogenetic analysis revealed that giant clams diverged from oyster about 505.7 Mya during the evolution of bivalves. The genome assembly presented here provides valuable genomic resources to enhance our understanding of the genetic diversity and population structure of giant clams

Assessment of the juvenile vulnerability of symbiont-bearing giant clams to ocean acidification

Ocean acidification (OA) severely affects marine bivalves, especially their calcification processes. However, very little is known about the fate of symbiont-bearing giant clams in the acidified oceans, which hinders our ability to develop strategies to protect this ecologically and economically important group in coral reef ecosystems. Here, we explored the integrated juvenile responses of fluted giant clam Tridacna squamosa (Lamarck, 1819) to acidified seawater at different levels of biological organization. Our results revealed that OA did not cause a significant reduction in survival and shell growth performance, indicating that T. squamosa juveniles are tolerated to moderate acidification. Yet, significantly reduced net calcification rate demonstrated the calcifying physiology sensitivity to OA, in line with significant declines in symbiont photosynthetic yield and zooxanthellae density which in turn lowered the amount of energy supply for energetically expensive calcification processes. Subsequent transcriptome sequencing and comparative analysis of differentially expressed genes revealed that the regulation of calcification processes, such as transport of calcification substrates, acid-base regulation, synthesis of organic matrix in the calcifying fluid, as well as metabolic depression were the major response to OA. Taken together, the integration of physiological and molecular responses can provide a comprehensive understanding of how the early life history stages of giant clams respond to OA and make an important leap forward in assessing their fate under future ocean conditions

Prevalence (%) of <i>S. japonicum</i> infection in bovines of different ages.

<p>*P<0.05;</p><p>**P<0.01 comparison of buffaloes younger and older than three years. C.N.,Cattle from Nandashan Town; B.N., Buffaloes from Nandashan Town; B.M., Buffaloes From Matang Town.</p

Prevalence of <i>S. japonicum</i> infection in buffalo and goats from Matang Town.

<p>*<i>P</i><0.05;</p><p>**<i>P</i><0.01 comparison of prevalence between buffalo and goats.</p>#<p><i>P</i><0.01 comparison of prevalence with that in 2005.</p

Overall prevalence and the number of infected domesticated ruminants.

<p>*The infected number of bovines was the sum of numbers of cattle and buffaloes, which were calculated with their total number (data not shown) and prevalence (in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031876#pone-0031876-t002" target="_blank">table 2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031876#pone-0031876-t003" target="_blank">3</a>) from each town. The numbers in brackets were from Matang Town.</p

Positive rates in field feces.

<p>Positive rates in field feces.</p

Prevalence of <i>S. japonicum</i> infection in cattle and buffalo from Nandashan Town.

<p>*<i>P</i><0.05;</p><p>**<i>P</i><0.01 comparison of prevalence between cattle and buffalo.</p