Comment on "A persistent oxygen anomaly reveals the fate of spilled methane in the deep Gulf of Mexico"

Kessler et al. (Reports, 21 January 2011, p. 312) reported that methane released from the 2010 Deepwater Horizon blowout, approximately 40% of the total hydrocarbon discharge, was consumed quantitatively by methanotrophic bacteria in Gulf of Mexico deep waters over a 4-month period. We find the evidence explicitly linking observed oxygen anomalies to methane consumption ambiguous and extension of these observations to hydrate-derived methane climate forcing premature.     

Chain Extension and Termination as a Function of Cysteine Content and the Length of the Central Repetitive Domain in Storage Proteins

Analogue glutenin proteins (ANGs) based on the barley seed storage protein C-hordein, modified to contain N- and/or C-terminal cysteine residues and varying lengths of repetitive domain, have been purified from a bacterial expression system. The proteins were used to modify the mixing, extension and baking properties of wheat flour doughs in small-scale tests. Comparison of the effects of simple addition of the proteins versus their chemical incorporation into the glutenin macropolymer has allowed us to assess the importance of cysteine content, cysteine position and repetitive domain length in determining dough mixing and processing properties. When incorporated, the proteins, along with small synthetic oligopeptides based on their N- and C-terminal sequences, change the amount of large glutenin polymers, and hence dough properties, in ways consistent with their action as either chain terminators (polypeptides with single cysteine residues) or chain extenders (polypeptides with two cysteine residues, one in either terminal domain). The gross effects of chain extension and termination may be further fine-tuned by modification of the molecular size of the incorporated proteins through alteration of their repetitive domains.     

Molecular Analysis of Potatoes from the Pacific Northwest Tri-State Variety Development Program and Selection of Markers for Practical DNA Fingerprinting Applications

DNA fingerprinting is a valuable tool for plant cultivar discrimination and identification. Simple Sequence Repeat (SSR) markers represent an excellent option for obtaining DNA fingerprints of potatoes in an easy, fast, and reliable fashion. The highly polymorphic and co-dominant nature of SSRs gives them good discrimination power to declare the distinctiveness of new potato clones for Plant Variety Protection (PVP) and to properly identify existing cultivars. They are also useful for confirming origin and avoiding duplications and mixtures in breeding, foundation and certification programs, and also during growing and marketing stages. A total of 54 (50 tetraploid and 4 diploid) potato clones, including new cultivars released by the Pacific Northwest Tri-State Potato Variety Development Program and a set of common commercial cultivars, were analyzed using 25 SSR markers. Marketing classes (French fry processing, fresh market, and chip processing) were clearly separated using those markers. We have empirically selected a subset of six SSRs that differentiate all the potato varieties and clones present in the study. This subset of six SSR markers could be used for practical DNA fingerprinting. In order to declare distinctiveness, we recommend that common reference varieties always be genotyped together with the newly tested potato clones and that focus be placed on the relative allelic differences between the new clones and the reference varieties.     

Antioxidant activities and anthocyanin content of fresh fruits of common fig (Ficus carica L.)

Fig fruit has been a typical component in the health-promoting Mediterranean diet for millennia. To study the potential health-promoting constituents of fig fruits, six commercial fig varieties differing in color (black, red, yellow, and green) were analyzed for total polyphenols, total flavonoids, antioxidant capacity, and amount and profile of anthocyanins. Using reversed-phase liquid chromatography (RP-LC), various concentrations of anthocyanins but a similar profile was found in all varieties studied. Hydrolysis revealed cyanidin as the major aglycon. Proton and carbon NMR confirmed cyanidin-3-O-rhamnoglucoside (cyanidin-3-O-rutinoside; C3R) as the main anthocyanin in all fruits. Color appearance of fig extract correlated well with total polyphenols, flavonoids, anthocyanins, and antioxidant capacity. Extracts of darker varieties showed higher contents of phytochemicals compared to lighter colored varieties. Fruit skins contributed most of the above phytochemicals and antioxidant activity compared to the fruit pulp. Antioxidant capacity correlated well with the amounts of polyphenols and anthocyanins (R2 = 0.985 and 0.992, respectively). In the dark-colored Mission and the red Brown-Turkey varieties, the anthocyanin fraction contributed 36 and 28% of the total antioxidant capacity, respectively. C3R contributed 92% of the total antioxidant capacity of the anthocyanin fraction. Fruits of the Mission variety contained the highest levels of polyphenols, flavonoids, and anthocyanins and exhibited the highest antioxidant capacity.     

The impact of drought on sorghum production,and farmer's varietal and trait preferences,in the north eastern Ethiopia: implications for breeding

Purpose: Sorghum [Sorghum bicolor (L.) Moench] has been cultivated for centuries as a staple food crop for millions of people in sub-Saharan Africa and Asia. In Ethiopia a total of 4.34 million tons of sorghum is being produced per annum, predominantly in the arid and semi-arid areas. However, the yield and quality of sorghum is affected by a wide array of production constraints, notably severe and recurrent drought stress. The aim of this study were to determine the impact of drought on sorghum production and productivity over time and space, and to identify farmers’ trait preferences, production constraints and coping strategies when dealing with drought in north eastern Ethiopia.

Materials and methods: Participatory rural appraisal (PRA) was employed in three administrative zones of north eastern Ethiopia. One Woreda from each Zone and two Kebeles from each Woreda were selected on the basis of sorghum area coverage, production, consumption and prior information on the intensity, duration and spatial coverage of drought. In each kebele, 30 respondents were selected for interview and 12 key informants were selected for group discussions and transect walk personal observations. Data collected from 180 respondents was subjected to statistical analysis and the information gathered from 72 key informants through focus group discussions and transect walk observations were used in discussing the results.

Results and discussion: The present study found that productivity of sorghum was challenged by recurrent droughts, Striga infestation, insects, birds, diseases, a lack of varieties with farmers-preferred traits and high yield potential, limited policy support, a lack of improved seed system, poor sorghum production practices and application of crop input and poor soil fertility, in a decreasing order of importance. Among the listed sorghum production constraints, severe drought in the post-flowering stage was identified by most interviewed farmers as the leading constraint across the three study zones. Focus group discussions and transect walk observations held in each Kebele revealed that farmers’ had lost numerous valuable local landrace varieties due to extreme drought conditions over the years. A significant number of interviewed farmers preferred to grow high grain and biomass yielder medium-maturing sorghum varieties which can be sown at the normal planting time but which would escape post-flowering drought.

Conclusion: Overall, sorghum breeding programme should be directed at developing farmers’ ideal sorghum varieties with high grain and biomass yield, adequate level of drought and Striga tolerance. In addition, development of farmer preferred medium-maturing sorghum varieties suitable for April planting should be strengthen to boost its productivity and to increase varietal adoption rate in the area.