Microbial production of recalcitrant dissolved organic matter: long-term carbon storage in the global ocean

The biological pump is a process whereby CO2 in the upper ocean is fixed by primary producers and transported to the deep ocean as sinking biogenic particles or as dissolved organic matter. The fate of most of this exported material is remineralization to CO2, which accumulates in deep waters until it is eventually ventilated again at the sea surface. However, a proportion of the fixed carbon is not mineralized but is instead stored for millennia as recalcitrant dissolved organic matter. The processes and mechanisms involved in the generation of this large carbon reservoir are poorly understood. Here, we propose the microbial carbon pump as a conceptual framework to address this important, multifaceted biogeochemical problem.National Basic Research Program of China [2007CB815904]; National Natural Science Foundation of China [40632013/40841023]; SOA project [201105021/DY1150243]; Gordon and Betty Moore Foundation ; US National Science Foundation [648116, 0752972, 0851113, MCB-0453993]; French Science Ministry [ANR07 BLAN 016]; Netherlands Organisation for Scientific Research-Earth and Life Science

Genome typing of nonhuman primate models: implications for biomedical research.

The success of personalized medicine rests on understanding the genetic variation between individuals. Thus, as medical practice evolves and variation among individuals becomes a fundamental aspect of clinical medicine, a thorough consideration of the genetic and genomic information concerning the animals used as models in biomedical research also becomes critical. In particular, nonhuman primates (NHPs) offer great promise as models for many aspects of human health and disease. These are outbred species exhibiting substantial levels of genetic variation; however, understanding of the contribution of this variation to phenotypes is lagging behind in NHP species. Thus, there is a pivotal need to address this gap and define strategies for characterizing both genomic content and variability within primate models of human disease. Here, we discuss the current state of genomics of NHP models and offer guidelines for future work to ensure continued improvement and utility of this line of biomedical research.peerReviewe

Stage-specific expression of proprotein form of hyaluronan binding protein 1 (HABP1) during spermatogenesis in rat

The presence of the 34-kDa hyaluronan binding protein 1 (HABP1) on sperm surface and its role in fertilization is already established (Ranganathan et al., 1994: Mol Reprod Dev 38:69-76). In the present communication, we examined the expression of HABP1 in adult rat testis during spermatogenesis. Interestingly, using anti-rHABP1 antibody, we detected a protein of 55 kDa which was present only in testis, but not in other somatic tissues like spleen and liver. However, even in testis, only one transcript of HABP1 mRNA of 1.63 kb was observed. In addition, we confirm that this testis-specific 55 kDa protein was immunologically identical with proprotein form of HABP1 using antibody raised against a decapeptide present in the proprotein region of HABP1. Comparative immunohistochemistry of testis, spleen, and liver tissues using both the antibodies supported the observation that the proprotein form of HABP1 is present only in testis. Higher mRNA expression of HABP1 in testis as compared to that of liver and spleen could be speculated from the RT-PCR product. Finally, detailed study of the immunohistochemical staining of the seminiferous tubules revealed the expression of the HABP1 proprotein in specific stages of germ cells, like pachytene spermatocytes and round spermatids, but not in elongated ones, suggesting a possible role of HABP1 proprotein in spermatogenic differentiation

Dynamics and diversity of newly produced virioplankton in the North Sea

Viral diversity has been studied in a variety of marine habitats and spatial and seasonal changes have been documented. Most of the bacteriophages are considered host specific and are thought to affect fast growing prokaryotic phylotypes more than slow growing ones. We hypothesized that viral infection and consequently, lysis occurs in pulses with only a few prokaryotic phylotypes lysed at any given time. Thus, we propose that the newly produced viruses represent only a fraction of the viral diversity present at any given time. Virioplankton diversity was assessed by pulsed-field gel electrophoresis in the surface waters of three distinct areas of the North Sea during the spring and summer. Bulk virioplankton diversity was fairly stable in these waters. Viral diversity produced by the indigenous bacterioplankton, however, exhibited day-to-day variability with only a few bands produced at any given time. These bands frequently matched bands of the in situ virioplankton; however, bands not present in the band pattern of the in situ virioplankton community were also found. These new bands probably indicate infection and subsequent release of viruses from bacterioplankton phylotypes previously not infected by these specific viruses. Overall, our results demonstrate that viral infection and lysis are rather dynamic processes. The main targets of viral infection are changing apparently on time scales of hours to days indicating that viral infection might effectively regulate and maintain bacterioplankton diversity