Exogenous Abscisic Acid Confers Salinity Tolerance in Chlamydomonas reinhardtii During Its Life Cycle.

The plant hormone abscisic acid (ABA) coordinates responses to environmental signals with developmental changes and is important for stress resilience and crop yield. However, fundamental questions remain about how this phytohormone affects microalgal growth and stress regulation throughout the different stages of their life cycle. In this study, the effects of ABA on the physiology of the freshwater microalga Chlamydomonas reinhardtii at its different life cycle stages were investigated.

Unconventional high-value products from microalgae: A review.

Microalgae have gained significant importance in biotechnology development, providing valuable goods and services in multiple applications. Although there is a rising market for most of these applications, the incorporation and introduction of microalgae into new venues will extend in the near future. These advances are due to the vast biodiversity of microalgal species, recent genetic engineering tools, and culture techniques.

Early evidence of royal purple dyed textile from Timna Valley (Israel).

In the context of a broad study aimed at examining dyeing technologies in the Timna textiles collection, three samples of prestigious fibers dyed with murex sea snail were identified. Our identification is based on the presence of 6-monobromoindigotin and 6,6-dibromoindigotin components (detected using HPLC analysis), which is considered unequivocal evidence for the use of murex-derived purple dyestuff. Furthermore, by comparing the analytical results with those obtained in a series of controlled dyeing experiments we were able to shed more light on the specific species used in the dyeing process and glean insights into the ancient dyeing technology.

Deep neural network recognition of shallow water corals in the Gulf of Eilat (Aqaba).

We describe the application of the computerized deep learning methodology to the recognition of corals in a shallow reef in the Gulf of Eilat, Red Sea. This project is aimed at applying deep neural network analysis, based on thousands of underwater images, to the automatic recognition of some common species among the 100 species reported to be found in the Eilat coral reefs. This is a challenging task, since even in the same colony, corals exhibit significant within-species morphological variability, in terms of age, depth, current, light, geographic location, and inter-specific competition.

Acclimation of thermotolerant algae to light and temperature interaction.

Here, we explore the responses of photosynthesis and related cellular processes in the thermotolerant microalga Micractinium sp. acclimated to limiting and saturating irradiances combined with elevated temperatures, using a novel computer-controlled multi-sensor system. This system allows for the monitoring of online values of oxygen exchange during photosynthesis and respiration with high accuracy.

Sensitivity study on the contribution of scattering by randomly oriented nonspherical hydrosols to linear polarization in clear to semi-turbid shallow waters.

The influence of hydrosol nonsphericity on the polarization characteristics of light under water is investigated by combining accurate single-scattering models for randomly oriented spheroidal scatterers with a radiative transfer model that employs Stokes formalism and considers refraction of direct unpolarized solar radiation and 100% linearly polarized radiation at the air-water interface followed by single scattering. Variations in what we call the "linear polarization phase function" (the degree of linear polarization as a function of scattering angle and the angle of linear polarization as a function of scattering angle) are examined for a wide range of spheroid aspect ratios and complex refractive indices of hydrosols. Implications for polarization-sensitive marine organisms and for remote sensing of the marine environment are discussed.

Sensitivity study on the effect of the optical and physical properties of coated spherical particles on linear polarization in clear to semi-turbid waters.

The influence of internal inhomogeneities within hydrosol particles on the polarization characteristics of light is investigated by combining an accurate coated sphere (core-shell) single-scattering model with a radiative transfer model that employs Stokes formalism and considers refraction of direct solar radiation at the air-water interface followed by single scattering. A Junge particle size distribution is assumed. Variations in what we call the "linear polarization phase function" (the degree of linear polarization as a function of scattering angle and the E-vector orientation as a function of scattering angle) are examined as a function of variations in the characteristics of the hydrosol particles.

Optimizing photon dose and frequency to enhance lipid productivity of thermophilic algae for biofuel production.

The aim of this work was to examine the potential of the thermophilic green microalga Micractinium sp. to accumulate triacylglycerols (TAGs) and to develop a light strategy to increase TAG productivity in this alga. To this end, dense cultures of Micractinium sp.

Early evidence (late 2nd millennium BCE) of plant-based dyeing of textiles from Timna, Israel.

In this article, we focus on the analysis of dyed textile fragments uncovered at an early Iron Age (11th-10th centuries BCE) copper smelting site during new excavations in the Timna Valley conducted by the Central Timna Valley (CTV) Project, as well as those found by the Arabah Expedition at the Hathor Temple (Site 200), dated to the Late Bronze/early Iron Ages (13th-11th centuries BCE). Analysis by HPLC-DAD identified two organic dyestuffs, Rubia tinctorum L. and indigotin, from a plant source (probably Isatis tinctoria L.

The spectral and spatial distribution of light pollution in the waters of the northern Gulf of Aqaba (Eilat).

The urbanization of the shores of the Gulf of Aqaba has exposed the marine environment there, including unique fringing coral reefs, to strong anthropogenic light sources. Here we present the first in situ measurements of artificial nighttime light under water in such an ecosystem, with irradiance measured in 12 wavelength bands, at 19 measurement stations spread over 44 square km, and at 30 depths down to 30-m depth. At 1-m depth, we find downwelling irradiance values that vary from 4.

Flashing light in microalgae biotechnology.

Flashing light can enhance photosynthesis and improve the quality and quantity of microalgal biomass, as it can increase the products of interest by magnitudes. Therefore, the integration of flashing light effect into microalgal cultivation systems should be considered. However, microalgae require a balanced mix of the light/dark cycle for higher growth rates, and respond to light intensity differently according to the pigments acquired or lost during the growth.

Continuous background light significantly increases flashing-light enhancement of photosynthesis and growth of microalgae.

Under specific conditions, flashing light enhances the photosynthesis rate in comparison to continuous illumination. Here we show that a combination of flashing light and continuous background light with the same integrated photon dose as continuous or flashing light alone can be used to significantly enhance photosynthesis and increase microalgae growth. To test this hypothesis, the green microalga Dunaliella salina was exposed to three different light regimes: continuous light, flashing light, and concomitant application of both.

Coral photobiology: new light on old views.

The relationship between reef-building corals and light-harvesting pigments of zooxanthellae (Symbiodinium sp.) has been acknowledged for decades. The photosynthetic activity of the algal endocellular symbionts may provide up to 90% of the energy needed for the coral holobiont.

Phytoplankton dynamics in the Gulf of Aqaba (Eilat, Red Sea): a simulation study of mariculture effects.

The northern Gulf of Aqaba is an oligotrophic water body hosting valuable coral reefs. In the Gulf, phytoplankton dynamics are driven by an annual cycle of stratification and mixing. Superimposed on that fairly regular pattern was the establishment of a shallow-water fish-farm initiative that increased gradually until its activity was terminated in June 2008.

Microbial rhodopsins on leaf surfaces of terrestrial plants.

The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 10(26) microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa).

Functional changes of the visual system of the damselfish Dascyllus marginatus along its bathymetric range.

Shallow-water zooplanktivorous fish rely on their vision for foraging. In shallow water, feeding efficiency decreases in dim light and thus the fish cease foraging at crepuscular hours. Creatures living in the lower parts of their depth ranges are expected to be exposed to limited light levels for longer hours.