AGRICULTURAL SCIENCES
Meat and milk from cloned bovines meet industry standards
Cindy Tian et al. report that meat and milk from cloned bulls and cows, respectively, appear to meet regulatory standards. The researchers cloned a Japanese Black beef bull and Holstein dairy cow, using somatic cell nuclear transfer, and compared the meat and milk from two beef clones and four dairy clones to that of genetic- and breed-matched control animals bred through conventional reproduction. Cloned and comparator animals received the same diet and were managed under the same conditions. Analysis of protein, fat, and other variables routinely assessed by the dairy industry revealed no significant differences in the milk compositions of the cloned and control cows. The authors examined >100 meat quality criteria, including organ and body part weights; total proportion of meat and fat in the dressed carcass; crude protein, fat, and moisture content in six muscles; fatty acid content in five major fat tissues; and overall organ histopathology. Approximately 90% of the criteria showed no statistically significant variations. Eight variables relating to the amount of fat and fatty acids in the meat were significantly higher in the meat from the clones. The authors say these higher fat levels are within beef industry standards.
Figure 1.
Meat from cloned bovines.
“Meat and milk compositions of bovine clones” by X. Cindy Tian, Chikara Kubota, Kunihito Sakashita, Yoshiaki Izaike, Ryoichi Okano, Norio Tabara, Carol Curchoe, Lavina Jacob, Yuqin Zhang, Sadie Smith, Charles Bormann, Jie Xu, Masumi Sato, Sheila Andrew, and Xiangzhong Yang (see pages 6261-6266)
EVOLUTION
Rapid evolution of energy production proteins in primates
Timothy Schmidt et al. report the observation of rapid evolution of cytochrome c oxidase (COX) at the cytochrome c (CYC) binding site in anthropoid primates. The COX enzyme complex catalyzes the transfer of electrons from CYC to oxygen in mitochondrial aerobic energy production. Previous research has shown that, in vertebrates, CYC and COX are largely conserved and have few amino acid replacements. Through structural analysis, Schmidt et al. identified 57 amino acids of COX that may bind CYC during electron transfer. The authors observed a significant acceleration of amino acid replacement rate in anthropoid primates compared with the tarsier, the most closely related nonanthropoid primate. From interspecies alignment of binding site residues, the authors found 27 changes from the earlier eutherians (placental mammalian ancestors) to humans, of which 59% were at electrostatically significant residue positions. The electrostatically significant changes occurred only in stem-anthropoids and stem-catarrhines, and few changes occurred in the ape and Old World monkey lineages. The researchers say that this reduction in amino acid replacement rate is consistent with the hypothesis that changes in ancestral lineages were advantageous and positively selected and, in descendent lineages, have been maintained by purifying selection.
Figure 2.
COX residues at CYC binding site.
“Rapid electrostatic evolution at the binding site for cytochrome c on cytochrome c oxidase in anthropoid primates” by Timothy R. Schmidt, Derek E. Wildman, Monica Uddin, Juan C. Opazo, Morris Goodman, and Lawrence I. Grossman (see pages 6379-6384)
IMMUNOLOGY
Priming of broad antitumor T cell responses
Veronika Groh et al. elicited broadly reactive antitumor responses by T cells primed by dendritic cells (DCs) sensitized with anti-MHC class I chain-related protein A (MICA) opsonized tumor cells. Immature DCs phagocytose damaged cells or infectious organisms and present peptides derived from protein degradation to CD8 and CD4 T cells on MHC class I and II molecules, respectively. Preferred methods used to prime T cells in vitro have relied on pulsing DCs with synthetic tumor antigen-derived MHC-binding peptides. Groh et al. coated melanoma, ovarian, or breast cancer cell lines or uncultured ovarian cancer cells with anti-MICA, an antibody to a protein expressed in diverse tumor types. The authors cocultured DCs from healthy donors with the opsonized cancer cells and found that the DCs primed significantly larger CD8 and CD4 T cell populations compared with DCs pulsed with antigenic peptides or cocultured with apoptotic tumor cells. DCs from tumor patients displayed a similarly increased ability to prime T cells. The authors further showed that primed CD8 T cells could lyse a broad variety of HLA-matched tumor cells, which were poor targets for peptide-primed T cells, and that primed CD8 and CD4 T cells had multivalent specificities against broad arrays of tumor antigens.
Figure 3.
Cross-priming of tumor-reactive CD4 T cells.
“Efficient cross-priming of tumor antigen-specific T cells by dendritic cells sensitized with diverse anti-MICA opsonized tumor cells” by Veronika Groh, Yongqing Q. Li, Daniel Cioca, Naomi N. Hunder, Wei Wang, Stanley R. Riddell, Cassian Yee, and Thomas Spies (see pages 6461-6466)
MICROBIOLOGY
Oceanic nitrogen loss controlled by bacteria
Marcel Kuypers et al. identified bacteria believed to be responsible for the massive nitrogen loss from the oxygen-poor region of the Benguela upwelling system off the coast of Namibia. Researchers previously attributed the nitrogen deficit in this oxygen-minimum zone (OMZ) to heterotrophic denitrification, a process in which denitrifying bacteria reduce nitrate to N2. Kuypers et al., however, used 15N incubations to provide evidence that anaerobic microbes combine ammonium and nitrite to form N2 gas via anaerobic ammonium oxidation (anammox). Anaerobic N2 production has recently been found to be a vital link in the Earth's nitrogen cycle. The authors quantified anammox bacteria in Namibian waters and demonstrated a linear correlation between anammox activity and the number of microorganisms. Primers specific for the bacteria Planctomycetes amplified the 16S ribosomal RNA gene from DNA isolated from seawater samples collected at various depths throughout the OMZ. Phylogenetic analyses of DNA revealed that the microorganisms were closely related to known anammox bacteria Scalindua sorokinii and Scalindua brodae. The authors conclude that anammox is a significant player in the removal of nitrogen from OMZ waters near Namibia and possibly in oceans around the world.
Figure 4.
Benguela upwelling system (white box).
“Massive nitrogen loss from the Benguela upwelling system through anaerobic ammonium oxidation” by Marcel M. M. Kuypers, Gaute Lavik, Dagmar Woebken, Markus Schmid, Bernhard M. Fuchs, Rudolf Amann, Bo Barker Jørgensen, and Mike S. M. Jetten (see pages 6478-6483)