Trans membrane domain IV is involved in ion transport activity and pH regulation of the NhaA-Na(+)/H(+) antiporter of Escherichia coli.

We have previously shown that the activity of NhaA is regulated by pH and found mutations that affect dramatically the pH dependence of the rate but not the K(m) (for Na(+) and Li(+)) of NhaA. In the present work, we found that helix IV is involved both in ion translocation as well as in pH regulation of NhaA. Two novel types of NhaA mutants were found clustered in trans membrane segment (TMS) IV: One type (D133C, T132C, and P129L) affects the apparent K(m) of NhaA to the cations with no significant effect on the pH profile of the antiporter; no shift of the pH profile was found when the activity of these mutants was measured at saturating Na(+) concentration. In contrast, the other type of mutations (A127V and A127T) was found to affect both the K(m) and the pH dependence of the rate of NhaA whether tested at saturating Na(+) concentration or not. These results imply that residues involved in the ion translocation of NhaA may (A127) or may not (D133, T132, and P129) overlap with those affecting the pH response of the antiporter. All mutants cluster in the N-terminal half of the putative alpha-helix IV, one type on one face, the other on the opposite. Cys accessibility test demonstrated that although D133C is located in the middle of TMS IV, it is inhibited by N-ethylmaleimide and is exposed to the cytoplasm.     

Possible congenital hemolytic anemia in prehistoric coastal inhabitants of Israel.

The spread of thalassemia among prehistoric populations of the Mediterranean Basin has been linked to the increased risk to early agriculturalists posed by the Plasmodium falciparum parasite. The diagnosis of the disease in human skeletal remains, however, has usually been based on a single pathological criterion, porotic hyperostosis. This paper reports on what we believe to be the earliest case of thalassemia yet identified in the prehistoric record. Our diagnosis of the disease in an individual from the submerged Prepottery Neolithic B village of Atlit-Yam off the Israeli coast is based on a pathological humerus demonstrating a pattern of deformation characteristic of clinical thalassemia. The implications of these findings for our understanding of human societies undergoing the transition from foraging to agriculture in the Near East are discussed.     

Quantification of Infection by Alternaria cassiae Using Leaf Immuno-Autoradiography and Radioimmunosorbent Assays

The severity of fungal infection is usually estimated visually as a rating of injury. A more quantitative method was needed to ascertain the effect of additives used to enhance the virulence of mycoherbicidal preparations. A sensitive and accurate serological method is presented for quantitative measurement of Alternaria cassiae infection of Cassia obtusifolia. An antiserum was prepared against a homogenate of mycelium of A. cassiae. A fast and simple procedure of leaf immuno-autoradiography was developed for the visualization of A. cassiae mycelium on inoculated leaves. A radioimmunosorbent assay (RISA) was developed for quantification of the extent of fungal infection. As little as 1. 6 ng/ ml dry weight equivalent of mycelium could be detected by RISA. There was a linear relationship between the logarithm of the RISA values and the logarithm of fungus concentration up to 300 ng/ml. Reduced sensitivity of the assay was pronounced in extracts containing 400 μ g/ml or more fresh weight of leaves. There was 30–40 % cross-reactivity of the antiserum with two other species of Alternaria, as well as with Monilinia fructicola, and almost no reactivity was found with three other fungi tested.     

8000 year-old human remains on the sea floor near Atlit,Israel

Our knowledge of prehistoric fishermen in the Eastern Mediterranean area is very scanty since most of the ancient coastal settlements are today inundated by the sea. The present paper describes and analyzes the human remains revealed and excavated in the 8,000 year-old submerged site at Atlit-Yam, Israel. The skeletal material indicates extensivce marine activities among the inhabitants of the village, including deep sea fishing, diving and fishnet production. The morphological similarity to the nearby Natufian population (Nahal Oren) points to population continuity in the region. The possibility of seafaring and relationships to pupulations of major mediterranean islands is also discussed.