The red-most fluorescence emission of photosystem I (733 nm at 4 K) is associated with the Lhca4 subunit of the antenna complex. It has been proposed that this unique spectral feature originates from the low energy absorption band of an excitonic interaction involving chlorophyll A5 and a second chlorophyll a molecule, probably B5 (Morosinotto, T., Breton, J., Bassi, R., and Croce, R. (2003) J....

Salinity is one of the most important abiotic stresses that limit crop growth and productivity. This study focuses on the effects of different strains of plant growth promoting rhizobacteria (PGPR) on the physiological responses of two wheat cultivars under normal and salt stress conditions. The wheat cultivars selected include one which is tolerant to salinity (Kavir) and one which is sensitiv...

Pigment photobleaching was performed in thylakoid membranes of Hordeum vulgare (wild type, mutant Chlorina f2, Norfluranzon treated seedlings) and in pigment-protein complexes (CP-I and LHCP) isolated from H. vulgare and Chlamydomonas reinhardtii. Multiphasic kinetics were obtained in all of the above cases. Energy transfer towards pigments absorbing at longer wavelength is postulated as a gene...

This is the first report on soybean with the aim to show the effects of gamma radiation on trichome metabolim. Soybean seeds were subjected to 300 Gy gamma radiation at a dose rate of 10 Gy/min using a Cs-137 gamma source. The photosynthetic pigment, total protein content and ascorbate peroxidase activity were studied. The results showed that the chlorophyll a content was decreased by 80% on da...

The abundance of aerobic anoxygenic phototrophic (AAP) bacteria, cyanobacteria, and heterotrophs was examined in the Mid-Atlantic Bight and the central North Pacific Gyre using infrared fluorescence microscopy coupled with image analysis and flow cytometry. AAP bacteria comprised 5% to 16% of total prokaryotes in the Atlantic Ocean but only 5% or less in the Pacific Ocean. In the Atlantic, AAP ...

Cyanobacterial harmful algal blooms (cyanoHABs) have been observed across the USA and worldwide, even locally in Lake Fayetteville (Arkansas, USA) once we started monitoring for total microcystin. The goal of this research note was to present a framework that might help guide cyanoHAB toxin public health advisories at Fayetteville. We evaluated nonparametric change points (i.e., thresholds) hie...

In both the warm pool region and the high-nutrient low-chlorophyll (HNLC) region of the equatorial Pacific, the phytoplankton community is dominated by high concentrations of picophytoplankton regardless of whether El Ni * no, La Ni * na or normal conditions prevail. Flow cytometry measurements indicate that the picoplankton community consists of two species of prokaryotes, Prochlorococcus and ...

Pigment composition and the pigment-protein complex of Symbionidium sp. strain Y106 isolated from the mantle lobe of Tridacna crocea were analyzed to investigate the photosynthetic machinery of this alga. High-performance liquid chromatography (HPLC) analysis was performed using a Waters Symmetry C8 column and a programmed binary gradient elution with a photodiode array detector. The pigments w...