Genetic studies of the Macushi and Wapishana Indians

Summary Blood samples from 509 Macushi and 623 Wapishana Amerindians of Northern Brazil and Southern Guyana have been analyzed with reference to the occurrence of rare variants and genetic polymorphisms of the following 25 systems: (i) Erythrocyte enzymes: acid phosphatase-1, adenosine deaminase, adenylate kinase-k, carbonic anhydrase-1, carbonic anhydrase-2, esterase A_1,2,3, esterase D, galactose-1-phosphate uridyltransferase, isocitrate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, nucleoside phosphorylase, peptidase A, peptidase B, phosphoglucomutase 1, phosphoglucomutase 2, phosphogluconate dehydrogenase, phosphohexoseisomerase, triosephosphate isomerase and (ii) Serum proteins: albumin, ceruloplasmin, haptoglobin, hemoglobin A, hemoglobin A₂ and transferrin. Fifteen different rare variants were detected, involving 11 of these systems. In addition, a previously undescribed variant of ESA_1,2,3 which achieves polymorphic proportions in both these tribes is described. Excluding this variant, the frequency of rare variants is 1.1/1000 in 12510 determinations in the Macushi and 4.7/1000 in 15 396 determinations in the Wapishana. The ESA_1,2,3, polymorphism was not observed in 382 Makiritare, 232 Yanomama, 146 Piaroa, 404 Cayapo, 190 Kraho and 112 Moro. Irregularities in the intratribal distribution of this polymorphism in the Macushi and Wapishana render a decision as to the tribe of origin impossible at present. Gene frequencies are also given for previosly described polymorphisms of 5 systems: haptoglobin, phosphoglucomutase 1, erythrocyte acid phosphatase, esterase D, and galactose-1-phosphate-uridyl-transferase.Research supported by the National Science Foundation and the Energy Research and Development Administration.     

Sensitivity and adaptation in R7, an ultraviolet photoreceptor,in theDrosophila retina

Summary Receptor deficient mutants and chromatic adaptation were used to isolate the contribution of R7 to the electroretinogram (ERG) ofDrosophila. R7 was found to be a single-peaked ultraviolet (UV) receptor (Fig. 1). Photoconversion of the UV absorbing rhodopsin (R) to its stable 470–495 nm metarhodopsin (M) was shown to elicit a long-lived negative (depolarizing) afterpotential (Fig. 3) while inactivating R7. Photoreconversion ofM toR reactivates R7 (Fig. 2) and repolarizes the ERG (Fig. 3). The intensities of light needed to elicit afterpotentials by photointerconverting R7 photopigment were found to be about 2 log units greater than for R1-6 photopigment (Fig. 4). Vitamin A deprivation decreases R7 (as well as R8) sensitivity by about 2 log units (through decreased photopigment levels) without changing spectral sensitivity shape (Fig. 5). Vitamin A deprivation further eliminates the light-induced inactivation of R7 allowing experiments designed to characterize the in vivo spectral absorption of R7M. R7M was found to have UV and 495 nm maxima (Fig. 6). No polarization sensitivity was detected in the R7 ERG component. The adaptational properties of R7 are similar to the properties previously established for R1-6 but different from the properties of R8.Supported by NSF grants BMS-74-12817 and BNS 76-11921. I thank M. Chapin, R. Greenberg, K. Hu, A. Ivanyshyn, D. Lakin, G. Pransky, D. Sawyer, J. Walker and W. Zitzmann for technical assistance.     

Lagomorph-constant region IgG allotypes: Shared e determinants inOchotona sp

The search for C allotypes as defined by the markers common to domestic rabbits (Oryctolagus) was extended to additional lagomorphs of the familiesLeporidae andOchotonidae. None of theOchotona sera obtained from Afghanistan and Iran (Ochotona rufescens) exhibited the d11, d12, or e14 allotypes. The e15 marker was detected only by radioimmune binding assays. Comparative inhibition of binding assays revealed similarities with other lagomorphs with respect to the e15i determinant. As in some variants of hare e15 markers, the e15j determinant is absent inOchotona. The results provided a revised phylogenetic scheme for the evolution of the C gene on the basis of the e-series allotypes.     

Genetics of graft-versus-host reactions (GVHR)

Injection of 20×10⁶ donor lymph node cells (LNCs) into newborn allogeneic recipients incompatible with donors at theIC subregion of the mouseH-2 complex evoked both GVH splenomegaly and GVH mortality. The strength or severity of the allogeneic reactions induced varied as a function of the interallelic strain combination and was influenced particularly by properties of the recipientIC determinants. Thus,IC ^s determinants on recipient cells led to strong GVHR, whileIC ^d determinants induced a moderate GVHR, even when donors carrying differentIC alleles were used. However, responder donor genes also affected the degree of GVHR in some combinations. The effect on donor GVH potential of pre-exposing B10 donors to antirecipient antiserum (B10 anti-B10.A) was also studied. Spleen cells from B10 donors pre-exposed to alloantiserum for two to seven days exhibited a markedly reduced ability to cause GVH splenomegaly and GVH disease in newborn B10. A or (B10. A × B10) F₁ recipients. Inhibition of donor lymphocyte GVH potential waned eight to 14 days after antiserum pretreatment. Inhibition was shown to be specific for variousH-2 determinants and to be caused by antirecipient alloantibodies. Pre-exposure of donors to alloantiserum reduced the GVH potential of spleen cells but did not affect LNC reactivity.Ia antibodies and, to a lesser extent, anti-H-2D serum were shown to be able to inhibit GVHR. The results suggest that the observed reduction in donor GVH reactivity is caused by antibody-mediated central feedback inhibition. Anti-H-2 alloantibodies evidently play an important role in the network regulating allogeneic responses.     

Gibberellic-acid-induced synthesis and release of cell-wall-degrading endoxylanase by isolated aleurone layers of barley

When aleurone layers of barley (Hordeum vulgare L.) are incubated with gibberellic acid (GA₃) xylose and arabinose—both as free sugars and bound to larger molecules—are released into the medium. Release begins 10–12h after the start of incubation and continues for at least 60h. At the same time there is a GA₃-induced breakdown of the cell wall resulting in a loss of 2/3 of the cell-wall pentose during 60h of incubation. GA₃ causes the appearance in the medium of an enzyme (or enzymes) which hydrolyze larchwood xylan and aleurone-layer arabinoxylan. Release of the enzyme(s) into the medium begins 28–32h after the start of incubation. Enzyme activity does not accumulate to any large extent in the tissue prior to release into the medium, and is present in very low levels only in the absence of GA₃. Xylanase activity is associated with a protein (or proteins) with a molecular weight of 29,000. The hydrolysis of the xylans is largely caused by endoxylanase activity, indicating the importance of endoglycosidases in the GA₃-induced breakdown of the aleurone cell wall.     

Metazoan arasites of fish from the Smallwood Reservoir, Labrador, Canada

Three-hundred and thirty-two fish of eight species (5 Salmo salar , 68 Salvelinus fontinalis , 32 S. namaycush , 102 Coregonus clupeaformis , 1 Prosopium cylindraceum , 107 Esox lucius , 14 Catostomus catostomus , 3 Couesius plumbeus ) from the Smallwood Reservoir, Labrador, Canada, were examined for metazoan parasites, using conventional parasitological techniques.
Fifteen genera of parasites were recovered (two of Monogenea, two of Digenea, four of Cestoda, three of Nematoda, two of Acanthocephala and two of Copepoda), these including seven new host records.
Significant differences were noted in the prevalence of the various parasites which were common to the different species of fish examined. No differences were recorded in the parasite burden of male and female fish. There was no correlation between the number of parasite species per infected fish and host age except in the case of Salvelinus namaycush . Food items of the fish examined were also noted.     

The role of myonuclei in muscle regeneration: An in vitro study

It is well established that during muscle regeneration, the satellite cells which are in a state of mitotic arrest, can initiate cell division to produce myoblasts which subsequently fuse to form myotubes. However, whether myonuclei, contained within damaged myotubes, or “freed” as a result of the trauma, play any role in muscle regeneration remains unresolved. In myogenic cultures, it is possible to obtain renewed myogenesis when initial cultures are sub-cultured. The aim of this study, was to obtain evidence of the participation by myonuclei of primary cultures in myogenesis which occurs subsequently in secondary cultures. In culture, myonuclei can be labelled with H³-thymidine and their ultimate fate, either as “free” myonuclei or myonuclei associated with disrupted myotubes can be followed unequivocally. Three types of experiments are performed: (i) Primary myogenic cultures containing only myotubes are subcultured. (ii) Primary myogenic cultures containing myotubes with labelled myonuclei are disrupted and subcultured. (iii) Primary myogenic cultures containing myotubes with unlabelled myonuclei are mixed with labelled mononucleated myogenic cells and sub-cultured. In all instances no evidence of myogenesis from myonuclei is obtained. It is concluded that myonuclei, which were rendered postmitotic during myogenesis, remain so when muscle is disrupted and cannot re-enter the mitotic cycle.     

Two new species of Enenterum Linton, 1910 (Digenea) in the marine fish Neoscorpis lithophilus (Kyphosidae) from the south-western Indian Ocean

Enenterum elsti sp. nov. and E. prudhoei sp. nov. are described from the intestine of Neoscorpis lithophilus off Mapelane, Natal, South Africa. These species differ from others of the genus Enenterum in the ratio of oral sucker to body-length and in the length of the prepharynx. E. elsti differs from E. prudhoei in size, in sucker-ratio and in the number and configuration of the oral lobes. A key to the species of Enenterum is presented and the status of the genus briefly discussed.     

Ion transport across the isolated intestinal mucosa of the winter flounder,Pseudopleuronectes americanus

The isolated intestinal mucosa of the flounder, Pseudopleuronectes americanus, when bathed in a 20 mM HCO3-Ringer's solution bubbled with 1% CO2 in O2, generated a serosa-negative PD and, when short-circuited, absorbed Cl at almost 3 times the rate of Na. Reducing HCO3 to 5 mM decreased the net Cl flux by more than 60%. The following results suggest that, despite the PD, Na and Cl transport processes are nonelectrically coupled: replacing all Na with choline abolished both the PD and net Cl flux; replacing all Cl with SO4 and mannitol abolished the PD and the net Na flux; and adding ouabain (to 0.5 mM) abolished the PD and the net Cl flux. Nearly all of the unidirectional serosa-to-mucosa Cl flux (JClsm) seemed to be paracellular since it varied with PD and Cl concentration in a manner consistent with simple diffusion. JClsm was only about one-fourth of JNasm, suggesting that the paracellular pathway is highly cation-selective. The data can be explained by the following model: (i) Na and Cl uptake across the brush border are coupled 1 : 1; Na is pumped into the lateral space and Cl follows passively, elevating the salt concentration there; (ii) the tight junction is permeable to Na but relatively impermeable to Cl; and (iii) resistance to Na diffusion is greater in the lateral space (considered in its entirety) than in the tight junction. If these assumptions are correct, the serosa-negative transmural PD is due mainly to a salt diffusion potential across the tight junction and, under short-circuit condition, most of the Na pumped into the lateral space diffuses back into the luminal solution, whereas most of the Cl enters the serosal solution. Morphological features of the epithelium support this interpretation: the cells are unusually long (60 micrometer); there is little distension of the apical 12 micrometer of the lateral space during active fluid absorption; and distension distal to this region is intermittently constricted by desmosomes.