Serologic evidence of a Rickettsia akari-like infection among wild-caught rodents in Orange County and humans in Los Angeles County, California.

We detected antibodies reactive with Rickettsia akari, the etiologic agent of rickettsialpox in humans and in 83 of 359 (23%) rodents belonging to several species, collected in Orange County, CA. Reciprocal antibody titers >1:16 to R. akari were detected in native mice and rats (Peromyscus maniculatus, P. eremicus, and Neotoma fuscipes) and in Old World mice and rats (Mus musculus, Rattus rattus, and R. norvegicus), representing the first time that antibodies reactive with this agent have been detected in four of these species and the first report of these antibodies in rodents and humans west of the Mississippi River. We then tested serum samples from individuals who used a free clinic in downtown Los Angeles and found that 25 of 299 (8%) of these individuals had antibody titers >1:64 to R. akari. Serologic evidence suggested that R. akari or a closely related rickettsia is prevalent among several rodent species at these localities and that infection spills over into certain segments of the human population. Isolation or molecular confirmation of the agent is needed to conclusively state that R. akari is the etiologic agent infecting these rodents.     

Activation of Integrin αVβ3 Regulates Cell Adhesion and Migration to Bone Sialoprotein

α_Vβ₃, a broadly distributed member of the integrin family of adhesion receptors, has been implicated in a variety of physiological and pathophysiological events, including control of bone density, angiogenesis, apoptosis, tumor growth, and metastasis. Recently, it has been shown that activation of α_Vβ₃, its transition from a low- to a high-affinity/avidity state, influences its recognition of certain ligands. Bone sialoprotein (BSP) is recognized as an important ligand for α_Vβ₃ in processes ranging from bone formation to the homing of metastatic tumor cells. Here, the influence of α_Vβ₃ activation on the adhesion and migration of relevant cells to BSP has been examined. Stimulation of lymphoblastoid, osteoblastoid, and human umbilical vein endothelial cells (HUVEC) with PMA or Mn²⁺ markedly enhanced α_Vβ₃-dependent adhesion to BSP. α_Vβ₃-mediated migration of HUVEC or osteoblastic cells to BSP was substantially enhanced by stimulation, demonstrating that α_Vβ₃ activation enhances both adhesive and migratory responses. However, adhesion and/or migration of certain tumor cell lines, including M21 melanoma and MDA MB435 and SKBR3 breast carcinoma cell lines, to BSP was constitutively high and was not augmented by α_Vβ₃-activating stimuli. Inhibitors of the intracellular signaling molecules, phosphatidylinositol 3-kinase with wortmannin, hsp90-dependent kinases with geldanamycin, and calpain with calpeptin, but not MAPKK with PD98059, reduced the high spontaneous adhesion and migration of the M21 cells to BSP, consistent with the constitutive activation of the receptor on these tumor cells. These results indicate that the activation state of α_Vβ₃ can regulate cell migration and adhesion to BSP and, by extension, to other ligands of this receptor. The constitutive activation of α_Vβ₃ on neoplastic cells may contribute to tumor growth and metastatic potential.     

The effects of lipoxygenase metabolites of arachidonic acid on human myometrial contractility

The effects of the lipoxygenase products of arachidonic acid, 5- and 12-hydroxyeicosatetraenoic acid (5- and 12-HETE) and leukotriene B4 (LTB4), on the spontaneous contractility of lower uterine segment human myometrial strips obtained prior to labour have been studied in vitro. 5-HETE gave a dose- dependent (10-500ng) increase in both the rate of contractions and overall contractility of myometrial strips while 12-HETE and LTB4 had no effect at the same concentrations. Prostaglandin F2 alpha (50ng) contracted all myometrial strips in a similar pattern to 5-HETE but was approximately 10 times more potent. The effect of 5-HETE may be direct or perhaps indirect via interaction with the cyclo-oxygenase pathway. The findings do not disprove the contention that the onset of parturition may be characterised by a switch in arachidonic acid metabolism in intra-uterine tissues from lipoxygenase to cyclo-oxygenase products.     

Polymorphisms of DQ β genes in HLA-DR4 haplotypes from healthy and diabetic individuals

The restriction fragment length polymorphism (RFLP) of DQ was assessed in a panel of control and insulin-dependent diabetes (IDD) patients who were serologically typed as HLA-DR4 homozygotes or HLA-DR3, DR4 heterozygotes. Digestions of genomic DNA with Barn HI, Bg1 II, Pst I, Xba I, and Hind III revealed a total of 15 RFLPs in the panel of 71 HLA-DR4 chromosomes. These RFLPs were organized into six allelic groups on the basis of segregation analysis in families. Complete RFLP haplotypes for the 5 restriction enzymes could be constructed for 42 of the HLA-DR4 chromosomes. This analysis revealed 18 RFLP haplotypes of DQ associated with the DR4 chromosomes tested. Two of these haplotypes, designated DQ3.DR4.a and DQ3.DR4.b, accounted for over 50 % of the DR4 chromosomes analyzed. These two haplotypes were antithetical for the RFLPs detected by all five enzymes, indicating that they represent very distinct forms of DQ . The remaining 16 haplotypes were infrequent or unique and were closely related to either a DQ3.DR4.a or DQ3.DR4.b. Two of the RFLPs detected, a 5.8 kb Bg1 II fragment and a 10.5 kb Barn HI fragment, had increased frequencies in disease-associated chromosomes. However, none of the RFLPs we detected exhibited a statistically significant increase in IDD or control populations. In contrast, the DQ3.DR4.b DQ haplotype was significantly decreased in IDD-associated DR4 chromosomes. (P=0.04). These results suggest that the DQ3.DR4.b DQ allele may be protective for the development of IDD.     

Characterization of phycoerythrin-containing Synechococcus spp. populations by immunofluorescence

Using an immunofluorescence assay developed to identify serogroups(i.e. clusters of strains labelled by one antiserum), the compositionof natural populations of phycoerythrin-containing Synechococcusspp. was examined. The 7803 (open ocean clone)-serogroup wasfound in most oceanic regions, but was most prevalent (up to85%) in tropical and subtropical waters during spring and summer.At coastal Long Island stations it was most abundant (up to65%) when water temperatures were >22°C. The seasonaland geographic distribution of the 7803-serogroup appeared tobe limited by water temperature. No consistent pattern was observedin the per cent composition with depth in the Sargasso Sea orat coastal to offshore stations in the North-west Atlantic Oceanor eastern tropical North Pacific Ocean. The 8016 (coastal clone)-serogroupwas abundant at coastal and estuarine stations off Long Island(up to 95 %) and its appearance was also correlated with warmwater temperature (> 15°C). However, this serogroup remaineda constant proportion of the population at the Long Island Soundstation during early winter months (through January) when abundanceof the 7803-serogroup was negligible. Owing to limited data,the oceanic distribution of the 8016-serogroup is not yet discernible.Lastly, antisera to the phycocyanin-dominant Synechococcus spp.clones failed to label any cells in samples collected from severaloceanic stations. Thus, these strains appear to be limited tocoastal and estuarine regions, which is consistent with predictionsfrom experiments comparing the photosynthetic performance ofthe phycoerythrin-dominant and phycocyanin-dominant clones. ¹Present address: Department of Oceanography, University ofHawaii, Honolulu, HI 96822, USA     

Thermal adaptations in lizard muscle function

Summary This study was undertaken to investigate thermal adaptations in muscle contractile properties in closely-related lizards with different preferred body temperatures (PBT). The species examined all belong to theSphenomorphus group of Australian skinks (Scincidae: Lygosominae). Preferred body temperatures are conservative at the generic level as follows:Ctenotus, 35°C;Sphenomorphus, 30°C;Eremiascincus, 25°C. Contractile properties of the fast glycolytic portion of the iliofibularis muscle were measured. Translational adaptations are evident in several isometric factors, including tetanic tension (Po), twitch tension (Pt), twitch time to peak tension (TPT), and twitch half-relaxation time (1/2 RT). Capacity adaptations are not evident in rates of tetanic tension development (dPo/dt) or in maximal velocities of isotonic shortening (V _max). Rotational adaptations are not evident in any contractile properties. Thermal limits on upper response temperatures are about 5°C warmer inCtenotus than in the more cryophilic species, indicative of resistance adaptation in muscle performance. Despite these adaptive shifts, there is little indication that muscle functional capacities are optimized or equalized at PBT in these lizards.Abbreviations FG fast glycolytic - IF iliofibularis muscle - PBT preferred body temperature - Po tetanic tension - Pt twitch tension - 1/2RT twitch half relaxation time - TPT twitch time to peak tension     

Biochemical Characterization of Molybdenum-Cofactor in a Cyanobacterium, Nostoc muscorum

Cell-free extracts of nitrate-grown Nostoc muscorum containnitrate reductase and molybdenum-cofactor activities. Whilenitrate reductase activity is associated with the paniculatefraction, cofactor activity is found predominantly in the solublefraction. This activity was distributed between two pools. Inone pool, the molybdenumcofactor is associated with a carrier(protein) of approximately 30,000 Da with an S_{20, w} between2.3 and 2.5. The carrier-bound cofactor is non-dialyzable andis found along with the major proteins during filtration inSephadex G-25 and G-100. The second pool contains free or unboundcofactor. It is separated from soluble proteins by dialysiswith a membrane with a pore-size of 10 to 15 kDa. However, itis retained with a membrane with a pore size of 1 kDa. It isin the included volume during chromatography through SephadexG-25. Its molecular mass is estimated to be between 1,000 and5,000 Da. The molybdenum content was proportional to cofactoractivity in both pools. Reducing agents increased cofactor activity.However, activity in both pools was sensitive to heat, acid,and oxidative treatments. The carrier protein appears to givesome protection. ¹Fulbright Scholar from Department of Biological Sciences, R.D. University, Jabalpur-482001, India. To whom reprint requestsshould be addressed. (Received June 22, 1987; Accepted August 21, 1987)     

Transport Properties of the Tomato Fruit Tonoplast : I. Identification and Characterization of an Anion-Sensitive H-ATPase

An anion-sensitive H⁺-translocating ATPase was identified in membrane vesicles isolated from mature green tomato (Lycopersicon esculentum) fruit. The H⁺-ATPase was associated with a low density membrane population having a peak density of 1.11 grams per cubic centimeter, and its activity was inhibited by NO₃⁻, N,N′-dicyclohexylcarbodiimide and diethylstilbestrol but not by vanadate, azide, molybdate, or oligomycin. This H⁺-ATPase has an unusual pH dependence indicating both a slightly acidic and a near neutral peak of activity. Chloride was found to be a potent stimulator of ATPase activity. The K_m for the H⁺-ATPase was approximately 0.8 millimolar ATP. The characteristics of this H⁺-ATPase are very similar to those described for a number of plant cell tonoplast H⁺-ATPases suggesting that the activity identified in tomato fruit membranes is tonoplast-associated. This report demonstrates the feasibility of isolating tonoplast vesicles from acidic fruit tissues for studies of transport activities associated with fruit development and maturation.     

The effect of the crossability loci Kr1 and Kr2 on fertilization frequency in hexaploid wheat x maize crosses

Summary Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes Highbury (kr1, Kr2) and Chinese Spring (Hope 5B) (kr1, kr2) were crossable with Seneca 60 maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in Chinese Spring (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.     

Structure of the platelet membrane glycoprotein IIb. Homology to the alpha subunits of the vitronectin and fibronectin membrane receptors

The platelet membrane glycoprotein IIb X IIIa heterodimer complex (GPIIb X IIIa) is the platelet receptor for adhesive proteins, containing binding sites for fibrinogen, von Willebrand factor, and fibronectin on activated platelets. GPIIb X IIIa also appears to be a member of a family of membrane adhesive protein receptors that plays a major role in cell-cell and cell-matrix interactions. GPIb is the larger component of this platelet receptor and is composed of two disulfide-linked subunits. In this report we describe the analysis of cDNA clones for human GPIIb that were isolated from a lambda gt11 expression library prepared using RNA from HEL cells. A total of 3.3 kilobases of cDNA was sequence, revealing a continuous open reading frame encoding both GPIIb subunits. The cDNA encodes 1039 amino acids: 137 constituting the smaller subunit, 871 constituting the larger subunit, and 30 constituting an NH2-terminal signal peptide. No homology was found between the larger and smaller subunits. The smaller subunit contains a 26-residue hydrophobic sequence near its COOH terminus that represents a potential transmembrane domain. Four stretches of 12 amino acids present in the larger subunit are homologous to the calcium binding sites of calmodulin and troponin C. Northern blot analysis using HEL cell RNA indicated that the mature mRNA coding for GPIIb is 4.1 kilobases in size. A comparison of the GPIIb coding region with available cDNA sequences of the alpha-chains of the vitronectin and fibronectin receptors revealed 41% DNA homology and 74% and 63% amino acid homology, respectively. Our data establish the amino acid sequence for the human platelet glycoprotein IIb and provide additional evidence for the existence of a family of cellular adhesion protein receptors.