Identification of a ferrireductase required for efficient transferrin-dependent iron uptake in erythroid cells

The reduction of iron is an essential step in the transferrin (Tf) cycle, which is the dominant pathway for iron uptake by red blood cell precursors. A deficiency in iron acquisition by red blood cells leads to hypochromic, microcytic anemia. Using a positional cloning strategy, we identified a gene, six-transmembrane epithelial antigen of the prostate 3 (Steap3), responsible for the iron deficiency anemia in the mouse mutant nm1054. Steap3 is expressed highly in hematopoietic tissues, colocalizes with the Tf cycle endosome and facilitates Tf-bound iron uptake. Steap3 shares homology with F(420)H(2):NADP(+) oxidoreductases found in archaea and bacteria, as well as with the yeast FRE family of metalloreductases. Overexpression of Steap3 stimulates the reduction of iron, and mice lacking Steap3 are deficient in erythroid ferrireductase activity. Taken together, these findings indicate that Steap3 is an endosomal ferrireductase required for efficient Tf-dependent iron uptake in erythroid cells.     

Action of stannous and stannic chlorides on bacteria

Summary Stannous or stannic chlorides reduced the growth rate ofK. aerogenes, Ps. reptilovora and an unidentified bacterium in a minimal liquid medium and on agar plates. The greatest effect was observed withK. aerogenes and was accompanied by a decreased viability, but 100% survival occurred with the other strains. The metal was loosely bound to the cells and there was no direct correlation between the amount adsorbed and the biological response.We are indebted to the Wolfson Foundation for a grant for research on natural resources.     

Clustering and isolation in the consensus problem for partitions

We examine the problem of aggregating several partitions of a finite set into a single consensus partition We note that the dual concepts of clustering and isolation are especially significant in this connection. The hypothesis that a consensus partition should respect unanimity with respect to either concept leads us to stress a consensus interval rather than a single partition. The extremes of this interval are characterized axiomatically. If a sufficient totality of traits has been measured, and if measurement errors are independent, then a true classifying partition can be expected to lie in the consensus interval. The structure of the partitions in the interval lends itself to partial solutions of the consensus problem Conditional entropy may be used to quantify the uncertainty inherent in the interval as a whole     

Essay review

Benjamin Franklin, the colonial American, maintained a now little-known interest in geological questions for more than sixty years. He began as a follower of English theorists, but soon assimilated some of their ideas with original speculations and discoveries, particularly regarding earthquakes. Though Franklin became famous for his experiments with electricity, he never attempted to explain earthquakes as if they were electrical phenomena; others, however, did. Through his access to American materials, Franklin contributed significantly to the work of several English and French geological theorists. Though some of his own theories were ultimately of limited value, Franklin played an important role in the international science of his time. In addition to his other accomplishments, he was colonial America's foremost student of geology.     

Growth processes in teeth distinguish modern humans from Homo erectus and earlier hominins.

A modern human-like sequence of dental development, as a proxy for the pace of life history, is regarded as one of the diagnostic hallmarks of our own genus Homo. Brain size, age at first reproduction, lifespan and other life-history traits correlate tightly with dental development. Here we report differences in enamel growth that show the earliest fossils attributed to Homo do not resemble modern humans in their development. We used daily incremental markings in enamel to calculate rates of enamel formation in 13 fossil hominins and identified differences in this key determinant of tooth formation time. Neither australopiths nor fossils currently attributed to early Homo shared the slow trajectory of enamel growth typical of modern humans; rather, both resembled modern and fossil African apes. We then reconstructed tooth formation times in australopiths, in the approximately 1.5-Myr-old Homo erectus skeleton from Nariokotome, Kenya, and in another Homo erectus specimen, Sangiran S7-37 from Java. These times were shorter than those in modern humans. It therefore seems likely that truly modern dental development emerged relatively late in human evolution.     

Econophysics for philosophers

In this essay review article I present a philosophers’ guide to econophysics, a relatively new field that applies the concepts and methods of statistical physics (and, more generally, other areas of physics) to economics (especially the economics of financial markets). I do this by looking at eleven recent books on econophysics.     

微波（2450MHZ）对离体人红细胞的损伤作用

为了观察微波对离体细胞的急性损伤效应，本文对微波辐射条件作了选择，用较高强度的微波（２４５０ＭＨｚ，１６～ｍｗ／ｃｍ＾２）辐射离体人红细胞３０分钟，结果表明红细胞溶血度和渗透脆性显著增高。而且在扫描电镜视野内，红细胞正常形态发生明显变化，且上述微波效应随辐射强度增大而增大。本文还以水浴加热组作对照，结果进一步显示微波对红细胞的生物学效应显著地大于常规水加热对样品生产的热损伤效应，这提示微波的表观热     

Breeding birds of an ancient bristlecone pine stand in east central Nevada

This paper describes features of the breeding bird population of a Great Basin ancient bristlecone pine stand on Wheeler Peak in White Pine County, east central Nevada. The bird population was determined by spot-mapping methods on a 20-ha plot during June and July 1981. The density of breeding birds was 82 pairs per 40 ha. Fourteen species were territorial. The most abundant species were the Dark-eyed Junco, Mountain Chickadee, Mountain Bluebird, and Townsend’s Solitaire. Other common breeding species included the Cassin’s Finch, Yellow-rumped Warbler, Pine Siskin, and Dusky Flycatcher. There were 410 individual breeding birds per km 2 . When expressed as standing crop biomass, the Townsend’s Solitaire was the predominant species, followed by the Dark-eyed Junco, American Robin, Mountain Bluebird, and Northern Flicker. Total standing crop biomass was 95 g/ha. None of the breeding birds were restricted to the bristlecone pine stand. The structure of the breeding bird community in the bristlecone pine forest compared best to those of the Rocky Mountain and Northern Boreal forest regions.