Globin genes in Polynesians have many rearrangements including a recently described gamma gamma gamma gamma/.

Rearrangements involving genes of the alpha- and beta-globin loci were frequently detected in DNA from Polynesians. A founder effect and genetic drift occurring 2,000-3,000 years ago as Polynesians migrated eastward across the Pacific is proposed as the likely mechanism for these genetic changes that include deletions or additions of alpha-, gamma-, and zeta-globin genes and an unusual restriction fragment length polymorphism (RFLP) associated with the zeta gene. Preliminary data show different frequencies for gene rearrangements between island groups. Further study of these differences should provide additional information on the prehistory of Polynesians.     

Mutational analysis of the receptor-activating region of human parathyroid hormone.

The first 4 residues of parathyroid hormone (PTH) are highly conserved in evolution and are important for biological activity. We randomly mutated codons 1-4 of human PTH (hPTH) with degenerate oligonucleotides and, after expression in COS cells, screened the mutants for receptor binding and cAMP-stimulating activity using ROS 17/2.8 cells. This survey identified Glu4 and Val2 as important determinants of receptor binding and activation, respectively. Positions 1 and 3 were more tolerant of substitutions indicating that these sites are less vital to hormone function. Activities of synthetic hPTH(1-34) analogs further demonstrated the importance of positions 2 and 4. The binding affinity of [Ala4,Tyr34] hPTH(1-34)NH2 was 100-fold reduced relative to [Tyr34]hPTH(1-34)NH2 (Kd values = 653 +/- 270 and 4 +/- 1 nM, respectively), and [Arg2, Tyr34]hPTH(1-34)NH2 was a weak partial agonist which bound well to the ROS cell receptor (Kd = 31 +/- 10 nM). The Arg2 analog was nearly as potent as PTH(3-34) as an in vitro PTH antagonist in osteoblast derived cells. However, unlike PTH(3-34), [Arg2]PTH was a full agonist in opossum kidney (OK) cells. These observations suggest that the activation domains of the OK and ROS cell PTH receptors are different. Thus, amino-terminal PTH analogs may be useful as probes for distinguishing properties of PTH receptors.     

Full-length chicken parathyroid hormone. Biosynthesis in Escherichia coli and analysis of biologic activity.

Chicken parathyroid hormone (cPTH) has been reported to stimulate adrenal steroidogenesis and to have unusual potency on traditional PTH target tissues. To evaluate these properties, chicken PTH-(1-88) has been expressed in Escherichia coli using a plasmid encoding a fusion protein which links together growth hormone, a factor Xa recognition site, and chicken PTH-(1-88). The growth hormone-cPTH fusion protein required the presence of 0.02% sodium dodecyl sulfate to remain in solution and be cleaved by factor Xa. The high performance liquid chromatography-purified recombinant cPTH-(1-88) and chemically synthesized cPTH-(1-34) had similar potency in rat osteosarcoma (ROS 17/2.8) cells, opossum kidney (OK) cells, and dispersed primary chicken kidney cells. The biologic potencies of cPTH-(1-34) and cPTH-(1-88) in radioreceptor binding and cAMP generation in both bone- and kidney-derived cell lines were less than those of human (h)PTH-(1-34). In dispersed chicken kidney cells, cAMP production by cPTH-(1-34) and cPTH-(1-88) was similar to that stimulated by human PTH-(1-34). No stimulation of steroidogenesis could be detected when recombinant chicken PTH-(1-88) was added to dispersed chicken adrenal cells. The biologic activity of recombinant chicken PTH-(1-88) purified from E. coli was comparable with that of chicken PTH-(1-88) expressed by mammalian COS cells. Thus, the full-length chicken PTH did not exhibit enhanced potency, when compared with human PTH in ROS 17/2.8, OK cell lines, and dispersed chicken kidney cells and did not demonstrate the novel steroidogenic action previously reported in adrenal cells. The successful production of chicken PTH-(1-88) will enhance our understanding of the structure-activity relationships for PTH, particularly the sequence-dependent metabolism of the hormone.     

A comparison of indices and measured values of eggshell thickness of different shell regions using museum eggs of 230 European bird species

The thickness of avian eggshells is used to assess shell quality in wild and domestic species, as an indicator of environmental pollution and as an adaptive explanation for shell maculation. Both direct measurements and calculated eggshell thickness indices (ETI) are used in such research, yet this is the first study to quantify, across a large spectrum of bird families (and thus egg shapes), the correlation between measured thicknesses and ETI. Furthermore, few studies have quantified thickness variation across the entire length of the shell, although this variation may influence both gas transfer and embryonic development. We measured the thickness of 942 eggshells of 230 European bird species from the Class II material at the Natural History Museum, Tring, UK, both in the conventional manner, at the equator through the blowhole and, uniquely, after a single longitudinal, cut at its equator at the blunt and pointed ends. Over half of the samples revealed shell defects, cautioning against the indiscriminate use of museum specimens. Strong positive associations were found between species‐specific means of shell thickness with each other and also with ETI, especially those derived from Schönwetter's ‘Handbuch der Oologie’ method, validating the interspecific comparative use of ETI. Thickness measurements and ETI factors are provided for all 230 species. Eggshells were usually thinner at the blunt end (the location of the air sac) than at the equator, but of equal thickness in passerine eggs. This difference was greatest in species producing elongate eggs and suggests that there is a functional significance of shell thickness variation among species that requires further investigation.     

Calcium signals regulate the functional differentiation of thymic iNKT cells

How natural or innate‐like lymphocytes generate the capacity to produce IL‐4 and other cytokines characteristic of type 2 immunity remains unknown. Invariant natural killer T (iNKT) cells differentiate in the thymus into NKT1, NKT2, and NKT17 subsets, similar to mature, peripheral CD4⁺ T helper cells. The mechanism for this differentiation was not fully understood. Here, we show that NKT2 cells required higher and prolonged calcium (Ca²⁺) signals and continuing activity of the calcium release‐activated calcium (CRAC) channel, than their NKT1 counterparts. The sustained Ca²⁺ entry via CRAC pathway in NKT2 cells was apparently mediated by ORAI and controlled in part by the large mitochondrial Ca²⁺ uptake. Unique properties of mitochondria in NKT2 cells, including high activity of oxidative phosphorylation, may regulate mitochondrial Ca²⁺ buffering in NKT2 cells. In addition, the low Ca²⁺ extrusion rate may also contribute to the higher Ca²⁺ level in NKT2 cells. Altogether, we identified ORAI‐dependent Ca²⁺ signaling connected with mitochondria and cellular metabolism, as a central regulatory pathway for the differentiation of NKT2 cells.     

Systemic NKT cell deficiency in NOD mice is not detected in peripheral blood: implications for human studies

In the diabetes-prone NOD mouse, there is a proven association between a systemic deficiency of NKT cells and the onset of type 1 diabetes. Numerous reports of similar defects within the NKT cell compartment of human type 1 diabetes patients suggested NKT cell levels might be a valuable predictor of susceptibility and could provide a target for therapeutic intervention. Two recent studies, however, found no association between type 1 diabetes and blood NKT cell levels in humans and consequently rejected a link between the onset of diabetes and NKT cell deficiency. This cast considerable doubts on the potential for NKT cell-based clinical applications and challenged the validity of the NOD mouse as a model of human type 1 diabetes. We now report that NKT cell levels in blood are a poor representation of those in other organs. Strikingly, systemic NKT cell deficiencies were identified in NOD mice with normal, or even raised, blood levels. This re-establishes the correlation between NKT cell deficiency and type 1 diabetes and raises important questions regarding the assaying of NKT cell levels in humans.