Fishers,dams, and the potential survival of the world's rarest turtle,Rafetus swinhoei,in two river basins in northern Vietnam

1. Next to cetaceans and megafishes, freshwater turtles are the most iconic endangered freshwater species.
2. A detailed questionnaire survey conducted with more than 100 individuals from fishing communities in northern Vietnam was used to investigate the current status of Southeast Asian turtles and provides new hope concerning the survival of Rafetus swinhoei, for which recent official records in the wild are limited to a single individual in Vietnam.
3. The survey included the entire Vietnamese portion of the Da River in Hoa Binh and Son La provinces, as well as the Chu and Ma river system in Thanh Hoa Province, as they are the last sites where the world's rarest and largest Asian softshell turtle has been seen. The questionnaire, conducted in Vietnamese, focused on demographic details, fishing intensity and gear, the status of fishing grounds, and the frequency of interaction with turtles.
4. The great majority of fishers could recognize different turtle species from photographs and describe their preferential breeding habitats; not all knew that they are protected. A few confirmed that more than once each year they still encounter freshwater turtles during their fishing activities.
5. This survey provides detailed information on sites where freshwater turtles are still seen in northern Vietnam and broadens our hope that wild individuals of the extremely rare R. swinhoei may still be present in the remaining riparian wetlands of these biodiverse, dammed, and controlled river basins in North Vietnam.

     

PCR-based markers to differentiate the mitochondrial genomes of petaloid and male fertile carrot (Daucus carota L.)

Cytoplasmic male sterility (CMS) is essential for the development of highly adapted and uniform hybrid varieties of carrot and other crops. The most widely used type of CMS in carrot is petaloidy, in which the stamens are replaced by petals or bract-like structures. We have developed a series of mitochondria-specific PCR markers to distinguish cytoplasms inducing petaloidy (Sp) and male-fertility (N). The markers target the atp1,atp6, atp9, orfB (atp8), nad6 and cob loci from the mitochondrial genomes of a diverse collection of male fertile and petaloid carrots. We report 14 primer pairs that amplify marker fragments from either Sp or N cytoplasms and three primer pairs that amplify fragments with length polymorphism. The amplification products span sites of insertions, deletions or recombinations adjacent to or within the coding regions of the targeted genes. The markers reported here are useful tools to identify the type of cytoplasm in cultivated carrot and to evaluate variation in the mitochondrial genomes within the genus Daucus. This revised version was published online in August 2006 with corrections to the Cover Date.     

Employment of flanking codominant STS markers to estimate allelic substitution effects of a nematode resistance locus in carrot

In carrot, two codominant sequence-tagged site (STS) markers, flanking in tight linkage the Meloidogyne javanica resistance (Mj-1) locus, were employed to investigate the association between expression of resistance and locus dosage. Phenotypic expression of homozygous resistant (R); heterozygous; and homozygous susceptible (S) individuals in an F₂ population of 396 F₂ plants from ‘Brasília-1252’ (R) × ‘B6274’ (S) was estimated for three resistance criteria: total egg production per plant (TEP), egg production per gram of fibrous root (EPG) and root gall index (RGI). The homozygous resistant class had average values of 403.9 for TEP; 147.5 for EPG and 0.8 for RGI. The heterozygous class had 1,673; 477.3; and 0.16 whereas the homozygous susceptible class had 68,604; 11,877; and 2.54, respectively. The dominance ratio (d/a) indicated that genomic region(s) derived from the resistant parent encompass genetic factor(s) with almost complete dominance for RGI (d/a = 0.93–0.94) and incomplete dominance for transformed (TEP)^0.25 and (EPG)^0.25 (d/a = 0.63–0.65). Broad sense heritabilities were high varying from 72.9% for (EPG)^0.25 to 86.0% for RGI. Narrow sense heritability values ranged from 55.9% for RGI to 64.3%for (TEP)^0.25. Highly significant orthogonal contrasts were observed between homozygous resistant vs. heterozygous for (TEP)^0.25 and (EPG)^0.25. Marker-assisted selection could greatly facilitate the incorporation of the Mj-1 allele in both male-fertile and male-sterile counterpart lines in order to obtain F₁ hybrids with the most effective levels of resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

H-2 antigen class: effect on mouse islet allograft rejection

Rejection of mouse pancreatic islet allografts occurred in a high percentage of donor recipient combinations identical for H-21-region antigens and differing at H-2K and H-2K + H-2D without I-region disparities. The results suggest that disparities in major histocompatibility complex antigens of class I (H-2K and H-2D) alone are capable of eliciting islet allograft rejection, and that lack of a stimulus from class II (I-region) alloantigens does not ensure permanent islet allograft survival.     

Hu-1: Major histocompatibility locus in man

A single locus with 15 or more alleles controls reactivity in mixed leukocyte culture tests. Genes at this locus also control most of the specificities measured by cytotoxic antiserums to leukocytes. Both of these tests can be used to predict survival of skin grafts. It is proposed that this is the major histocompatibility locus in man.     

Function of the methanogenic community in mangrove soils as influenced by the chemical properties of the hydrosphere

Coastal ecosystems represent a potential additional source of the greenhouse gas methane (CH₄) that has been insufficiently quantified. Thus, to understand the mechanisms controlling greenhouse gas emissions in these ecosystems, this study investigated CH₄ emissions from and the related microbial properties of mangrove soils. Soil and gas samples were collected from several plots at different distances from the seashore in Soc Trang and Ca Mau in Vietnam, and the Sundarbans in India. Soil samples were incubated under different conditions, i.e., anaerobic or aerobic, and the microbial properties of each soil sample with the addition of different amounts of seawater were analyzed. Relatively high CH₄ fluxes and production were detected during the aerobic incubation of samples from the seashore plots in Soc Trang and Ca Mau. However, CH₄ production was reduced under anaerobic conditions [soil electrical conductivity (EC): 179–289 mS m^?1, pH (H₂O): 7.45–8.10] compared with aerobic conditions [water content: 38.9–109.2%, EC: 187–299 mS m^?1, pH (H₂O): 6.86–7.72], but it increased with increasing sulfate concentration, soil EC and cellulase activity and lowering soil pH under anaerobic conditions. Furthermore, mangrove soil with a relatively high level of total organic carbon (C) exhibited relatively high CH₄ production when diluted 4-fold with seawater under anaerobic conditions [water content: 38.9–109.2%, EC: 533 mS m^?1, pH (H₂O): 6.67]. Nearly all of the DNA bands excised from polymerase chain reaction-denaturing gradient gel electrophoresis contained identical sequences related to archaea from the class Halobacteria. The high potential of the seashore plot for CH₄ emissions could be due to the enhancement of cellulase activity under the intermittent oxygen supply, which promotes polysaccharide depolymerization and subsequently increases anaerobic methanogenic activities during tidal flooding. This study also indicates that the major archaea responsible for CH₄ production require a particular hydrospheric salt concentration and soil pH.     

Characteristics of senescent straw cell walls of dwarf, semidwarf, and normal strains of rice (Oryza sativa) plants

A normal variety of rice (Oryza sativa L.cv. Taichung 65, T65c), its isogenic dwarf line (T65d ₁), and a semidwarf variety of a different line (Oryza sativa L.cv. IR8, IR8) were studied. The results were compared with those of an isogenic dwarf line (Rh _i) of wheat straw, which was previously reported. Expression of the dwarf gene,d ₁, on the chemical composition and the structural features of lignin present in rice internodes differs from that in an isogenic dwarf line of wheat. The differences include the lignin content, total yield of alkaline nitrobenzene oxidation products, and distribution of wall-bound hydroxycinnamic acids. There was, however, no difference in the syringyl/ guaiacyl nuclei (S/V) molar ratio and neutral sugar composition. The lignin composition of rice straw cell walls, particularly that of the dwarf variety, contained more of the condensed structure and fewer syringyl nuclei than lignin in wheat straw cell walls. It is suggested that crosslinking between lignin and polysaccharides by ester-ether bridges via ferulic acid contributes to the mechanical properties of the cell walls of rice straw. Thus the chemical and structural characteristics of lignin in rice straw differ to some extent from those of other temperate grasses, such as wheat (Triticum aestivum) and phalaris (Phalaris aquatica), as reported previously. This can probably be attributed to the water environment of rapidly growing rice seedlings, but it also depends on the genetic variety of the rice plant.     

Effect of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the gastrointestinal tract of growing pigs

The main objective of the present investigation was to study the impact of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the small intestine and total tract of growing pigs. Eight pigs (initial BW, 34.5 ± 0.9 kg) were used in a replicated 4 × 4 Latin square design. Pigs were cannulated and housed individually in metabolism pens during sample collection. The 4 cereal-based diets were nonfermented liquid barley (NFLB), nonfermented liquid wheat (NFLW), fermented liquid barley (FLB), and fermented liquid wheat (FLW). The fermented feeds were prepared by storing the dietary cereals (barley and wheat) and water [1:2.75 (wt/wt)] in a closed tank at 25 °C for 2 d, after which 50% of the volume was removed and replaced with an equal amount of fresh cereals and water after each afternoon meal. At the time of feeding (0730 and 1430 h), the remaining dietary ingredients were added. Water was added to the dry nonfermented feeds [1:1 (wt/wt)] immediately before feeding. The fermentation process reduced the amount of DM in both cereals (P<0.001), whereas the amount of DM was similar (P=0.626) between the fermented cereals. There was an interaction of cereal and treatment for ileal flow of DM (P=0.014), OM (P=0.013), and protein (P=0.006), which were less in pigs fed the NFLB than the FLB diets, but unchanged in pigs fed the NFLW and FLW diets. Conversely, the ileal flow of protein was similar (P=0.605) in pigs fed the barley diets (average, 47.5 ± 1.7 g/kg of DMI) and increased with the FLW diet compared with the NFLW diet (43 vs. 35 g/kg of DMI, respectively). Ileal fat and CH(2)O digestibilities were 7.6 (P=0.002) and 8.9% (P<0.001) greater, respectively, when pigs were fed wheat compared with the barley-based diets, and the ileal digestibility of CH(2)O was greater when pigs were fed the fermented than nonfermented diets (86.5 vs. 84.5%, respectively; P<0.001). Fermentation reduced (P<0.0001) the fecal excretion of DM, OM, and protein in pigs fed the barley diet, but not when fed the wheat-based diet (P=0.305). Fermentation had no effect (P=0.243) on the fecal digestibility of nonstarch polysaccharides in either of the cereals but their digestibility was 10.0% greater (P<0.001) in pigs fed wheat than the barley-based diets. In conclusion, fermentation of cereal before feeding altered the dietary composition and influenced flow and composition of polysaccharides and other macronutrients at the ileum and in feces to a larger extent for barley than wheat.