Isotopic characteristics (δ13C, δ15N, and δ18O) of honey from Bangladesh retail markets: Investigating sugar manipulation, botanical and geographical authentication

The study analyzed stable isotope composition (carbon, nitrogen, oxygen) of Bangladesh origin monofloral and multifloral honey for the first time to identify the C-4plant sugar adulteration, botanical and geographical differentiation. The C-4 sugar content (11.90 to 86.61%) using carbon isotope values of whole honey and protein extractidentified18% adulterated honeys.Whereas 82% honey have been detected as authentic with the δ13C ranges from -24.86 to -29.26‰ and the C-4 sugar values ranges from -6.75 to 5.67%. The chemometric approach using carbon and nitrogen isotopesvalues revealed discrimination among floral types of Bangladeshi authentic honeys indicating the influence of botanical source on isotopic composition. Canonical discriminant analysis (CDA) of C and N isotopes showed geographic distinction among Bangladeshi and overseas origin honeys. It is notable that the black seed honeys were correctly classified with the CDA analysis representing this type as unique Bangladesh brand as New Zealand manuka honey.

Impact of gamma radiation, potassium sorbate and low temperature on shrimp (Penaeus monodon) preservation

The objective this study was to assess the effect of gamma radiation and 2% potassium sorbate with low temperature (4 °C) for shrimp (Penaeus monodon) preservation. Fresh samples were prepared for treatment with gamma radiation at 1.0 and 1.5 kGy doses and potassium sorbate (2%) soaked for 30 s (PS 30 s) and 60 s (PS 60 s). Organoleptic score (OS), biochemical composition and microbiological analysis were performed to evaluate the shelf-life extension and quality changes during the storage periods. Data showed that combination treatment of gamma irradiation at 1.5 kGy with low temperature was the most effective in extending shelf-life of shrimp. The isolated bacteria associated with shrimp samples were identified through PCR technique. Antibiotic sensitivity test was examined using ten commonly used antibiotics against these pathogenic isolates. Gentamicin and Imipenem showed up to 50% resistance on Gram-positive (Bacillus cereus and Staphylococcus aureus). This study indicates that gamma irradiation treatment with low temperature was most effective way for shelf-life extension of shrimp which might reduce the wastage of this important nutritional source.

Chlororespiratory reduction 6 is a novel factor required for accumulation of the chloroplast NAD(P)H dehydrogenase complex in Arabidopsis

The chloroplast NAD(P)H dehydrogenase (NDH) complex is involved in photosystem I cyclic electron transport and chlororespiration in higher plants. An Arabidopsis (Arabidopsis thaliana) chlororespiratory reduction 6 (crr6) mutant lacking NDH activity was identified by means of chlorophyll fluorescence imaging. Accumulation of the NDH complex was impaired in crr6. Physiological characterization of photosynthetic electron transport indicated the specific defect of the NDH complex in crr6. In contrast to the CRR7 protein that was recently identified as a potential novel subunit of the NDH complex by means of the same screening, the CRR6 protein was stable under the crr2 mutant background in which the NDH complex does not accumulate. The CRR6 gene (At2g47910) encodes a novel protein without any known motif. Although CRR6 does not have any transmembrane domains, it is localized in the thylakoid membrane fraction of the chloroplast. CRR6 is conserved in phototrophs, including cyanobacteria, from which the chloroplast NDH complex has evolutionally originated, but not in Chlamydomonas reinhardtii, in which the NDH complex is absent. We believe that CRR6 is a novel specific factor for the assembly or stabilization of the NDH complex.

Chlororespiratory reduction 6 is a novel factor required for accumulation of the chloroplast NAD(P)H dehydrogenase complex in Arabidopsis

The chloroplast NAD(P)H dehydrogenase (NDH) complex is involved in photosystem I cyclic electron transport and chlororespiration in higher plants. An Arabidopsis (Arabidopsis thaliana) chlororespiratory reduction 6 (crr6) mutant lacking NDH activity was identified by means of chlorophyll fluorescence imaging. Accumulation of the NDH complex was impaired in crr6. Physiological characterization of photosynthetic electron transport indicated the specific defect of the NDH complex in crr6. In contrast to the CRR7 protein that was recently identified as a potential novel subunit of the NDH complex by means of the same screening, the CRR6 protein was stable under the crr2 mutant background in which the NDH complex does not accumulate. The CRR6 gene (At2g47910) encodes a novel protein without any known motif. Although CRR6 does not have any transmembrane domains, it is localized in the thylakoid membrane fraction of the chloroplast. CRR6 is conserved in phototrophs, including cyanobacteria, from which the chloroplast NDH complex has evolutionally originated, but not in Chlamydomonas reinhardtii, in which the NDH complex is absent. We believe that CRR6 is a novel specific factor for the assembly or stabilization of the NDH complex.

Identification of a novel protein, CRR7, required for the stabilization of the chloroplast NAD(P)H dehydrogenase complex in Arabidopsis

An Arabidopsis thaliana mutant, crr7 (chlororespiratory reduction), was isolated using chlorophyll fluorescence imaging to detect reduced activity in NAD(P)H dehydrogenase (NDH). The chloroplast NDH complex is considered to have originated from cyanobacteria in which the NDH complex is involved in respiration, photosystem I (PSI) cyclic electron transport and CO2 uptake. In higher plants the NDH complex functions in PSI cyclic electron transport within the chloroplast. Despite exhaustive biochemical approaches, the entire subunit composition of the NDH complex is unclear in both cyanobacteria and chloroplasts. In crr7 accumulation of the NDH complex was specifically impaired. In vivo analysis of electron transport supported the specific loss of the NDH complex in crr7. CRR7 (At5g39210) encodes a protein of 156 amino acids, including a putative plastid target signal, and does not contain any known motifs. In contrast to CRR2 and CRR4, involved in the expression of chloroplast ndh genes, CRR7 is conserved in cyanobacterial genomes. Although CRR7 did not contain any transmembrane domains, it localized to the membrane fraction of the chloroplast. CRR7 was unstable in the crr2-2 mutant background, in which the expression of ndhB was impaired. These results strongly suggest that CRR7 is a novel subunit of the chloroplast NDH complex.