Marina Temina

Natural microbial UV radiation filters — Mycosporine-like amino acids

Ozone depletion by anthropogenic gases has increased the atmospheric transmission of solar ultraviolet-B radiation (UV-B, 280–315 nm). There is a logical link between the natural defenses of terrestrial and marine organisms against UV radiation and the prevention of UV-induced damage to human skin. UV light degrades organic molecules such as proteins and nucleic acids, giving rise to structural changes that directly affect their biological function. These compounds offer the potential for development of novel UV blockers for human use. The biological role of mycosporine-like amino acids (MAAs) and scytonemin as a defense against solar radiation in organisms, together with their structure, synthesis, distribution, regulation and effectiveness, are reviewed in this article. This review points to the role of MAAs as a natural defense against UV radiation.

An Investigation of the Role of Water (Rain and Dew) in Controlling the Growth Form of Lichens on Cobbles in the Negev Desert

Dew and rain were measured along the north facing slope (NFS, with epilithic lichens predominating) and the south-facing slope (SFS, with endolithic lichens predominating) in the Negev (P = 95 mm) in order to evaluate the relationships between the abiotic conditions and the lichen growth form. Although insignificant differences characterize the rain and dew amounts with the epilithic growth form, high correlation was obtained between dew duration (r2 = 0.73) and the combined duration of dew and rain (r2 = 0.79). The data imply that daylight wetness duration rather than the amount of precipitation may explain the predominance of epilithic lichens at the shaded NFS.

The Effect of Dew and Fog on Lithic Lichens Along an Altitudinal Gradient in the Negev Desert

The effect of dew upon lichen communities was studied in three sites along an altitudinal gradient in the Negev Desert. The sites [Nizzana, NIZ (250m a.s.l), Sede Boqer, SB (530m a.s.l.) and Har Harif, HH (990m a.s.l.)] have similar rain precipitation (∼100 mm) but different dew precipitation of 0.11, 0.21 and 0.32 mm, respectively. A clear gradient was found for the chlorophyll content with NIZ (38.6 mg m−2)<SB (52.6 mg m−2)<HH (71.3 mg m−2), and the epilithic growth form with NIZ (1.4%) < SB (4.3%) ≪ HH (53.6%) highlighting the fundamental role played by dew in dictating the structure of lichen communities. The findings may assist us in identifying lichens that may serve as biomarkers for dew availability and in anticipating changes in the lichen communities following global warming.

Lichen Colonization on Cobbles in the Negev Desert Following 15 Years in the Field

Rock slabs were placed from 1991 through 2006 at the bottom of a north- (NFS) and a south-facing (SFS) slope of a first order drainage basin in the Negev Desert Highlands, Israel (P = 95 mm) where natural cobbles have >95% cover of endolithic and epilithic lichens. Periodic measurements of rain, dew and chlorophyll content took place. Lichen cover and the regeneration time were aspect-dependent. Lichen cover was 98% and 61% at NFS and SFS, respectively, while the lichens recovery time was respectively ∼45 and ∼80 years. The fast regeneration time may have important implications regarding weathering and soil formation.

The Mycobiont Role in Crustose Lichen Expansion on Cobbles in the Negev Desert

Whereas the role of the photobiont within microlichen symbiosis is indisputable, the role of the mycobiont in the symbiosis is still questionable. Here we report a unique expansion of the endolithic lichen Caloplaca alociza on cobbles in the Negev Desert due to structural change induced by the mycobiont burrowing activity. By increasing the water-holding capacity of the rock it facilitates lichen expansion from the cobble margins (where they establish due to water capillary rise) to its sides. And thus, while rare at the cobble top, lichen expansion is taking place to the sides of the cobble albeit the fact that dew (the main water source) is significantly lower at the cobble sides than at its top.

New Records of Lichens from Mount Carmel National Park and Atlit Beach (Israel)

Abstract: Temina, M. & Brodo, I. M. 2013. New records of lichens from Mount Carmel National Park and Atlit Beach (Israel). — Herzogia 26: 91—102. Details of 27 lichen species from Mount Carmel National Park and 9 species from Atlit Beach are presented, of which 10 species (Arthonia albopulverea, A. pinastri, Bacidia circumspecta, Caloplaca navasiana, C. oasis, Collema subnigrescens, Enterographa crassa, Gyalecta truncigena, Lecania spadicea and Lecanora symmicta) are new to Israel.