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R Anker

Publications and source records attributed to R Anker.

18 recordsLinked to original sources
PubMed1996

Mapping human telomere regions with YAC and P1 clones: chromosome-specific markers for 27 telomeres including 149 STSs and 24 polymorphisms for 14 proterminal regions.

A YAC library enriched for telomere clones was constructed and screened for the human telomere-specific repeat sequence (TTAGGG). Altogether 196 TYAC library clones were studied: 189 new TYAC clones were isolated, 149 STSs were developed for 132 different TY-ACs, and 39 P1 clones were identified using 19 STSs from 16 of the TYACs. A combination of mapping methods including fluorescence in situ hybridization, somatic cell hybrid panels, clamped homogeneous electric fields, meiotic linkage, and BLASTN sequence analysis was utilized to characterize the resource. Forty-five of the TYACs map to 31 specific telomere regions. Twenty-four linkage markers were developed and mapped within 14 proterminal regions (12 telomeres and 2 terminal bands). The polymorphic markers include 12 microsatellites for 10 telomeres (1q, 2p, 6q, 7q, 10p, 10q, 13q, 14q, 18p, 22q) and the terminal bands of 11q and 12p. Twelve RFLP markers were identified and meiotically mapped to the telomeres of 2q, 7q, 8p, and 14q. Chromosome-specific STSs for 27 telomeres were identified from the 196 TYACs. More than 30,000 nucleotides derived from the TYAC vector-insert junction regions or from regions flanking TYAC microsatellites were compared to reported sequences using BLASTN. In addition to identifying homology with previously reported telomere sequences and human repeat elements, gene sequences and a number of ESTs were found to be highly homologous to the TYAC sequences. These genes include human coagulation factor V (F5), Weel protein tyrosine kinase (WEE1), neurotropic protein tyrosine kinase type 2 (NTRE2), glutathione S-transferase (GST1), and beta tubulin (TUBB). The TYAC/P1 resource, derivative STSs, and polymorphisms constitute an enabling resource to further studies of telomere structure and function and a means for physical and genetic map integration and closure.

Animals↗
PubMed1995

Recombinant mapping of the familial hyperinsulinism gene to an 0.8 cM region on chromosome 11p15.1 and demonstration of a founder effect in Ashkenazi Jews.

A gene for autosomal recessive familial hyperinsulinism (HI) (OMIM: 256450), a neonatal metabolic disease characterized by inappropriate insulin secretion in the presence of severe hypoglycemia, was recently mapped to a 6.6 cM interval between the markers D11S926 and D11S928 on chromosome 11p in 15 families (1). In the current study we evaluated six additional families and five new markers, and further localized the gene between D11S419 and D11S1310. Using genotype data from CEPH Version 7 and data generated from this study, this region was estimated to be 0.8 cM in length. Significant linkage disequilibrium between markers and the HI gene was observed over a region of 10.3 cM (11 pter-D11S926-D11S1308-11pcen) for Ashkenazi Jewish chromosomes. Haplotype analysis showed that 12 of 36 HI chromosomes, versus one of 36 non-HI chromosomes, bore a specific haplotype for D11S419-D11S902-D11S921 (p < 0.0007), strongly suggesting a founder effect in this ethnic group.

Alleles↗
PubMed1994

Familial hyperinsulinism maps to chromosome 11p14-15.1, 30 cM centromeric to the insulin gene.

Familial hyperinsulinism (HI) is the most common cause of persistent neonatal hyperinsulinaemic hypoglycemia. Linkage analysis in 15 families (12 Ashkenazi Jewish, 2 consanguineous Arab, 1 non-Jewish Caucasian) mapped HI to chromosome 11p14-15.1 (lod score = 9.5, theta = 0 at D11S921). Recombinants localized the disease locus to the 6.6 cM interval between D11S926 and D11S928. In Jewish families, association (p = 0.003) with specific D11S921/D11S419 haplotypes suggested a founder effect. This locus, which is important for normal glucose-regulated insulin secretion, represents a candidate gene for studies of other diseases of beta-cell dysfunction including non-insulin-dependent diabetes mellitus (NIDDM).

Chromosome Mapping↗
PubMed1991

Co-expression of full-length and truncated Ig mu-chains in human B lymphocytes results from alternative splicing of a single primary RNA transcript.

A survey of Ig synthesis among mu-heavy chain-producing human B cell lines indicated that roughly one-third co-express full length (mu+) and a particular type of truncated mu-chain (designated mu'). The relative molecular size of the intracellular form of this truncated mu-chain and its normal pattern of N-glycosylation suggested that mu'-chains were missing a single Ig domain at the protein level. Cell-free translation of polyA+ RNA from mu'-producing human B cell lines generated appropriate mu'-translation products, and Northern blot analysis demonstrated the presence of correspondingly truncated mu'-transcripts in these lines. These results pointed to a pretranslational basis for mu+/mu' co-expression. Sequencing of mu+- and mu'-cDNA clones from two human B cell lines showed that mu+- and mu'-transcripts derive from the same primary transcript, with mu'-mRNA formed by a direct leader-to-C mu 1 exon splice such that the heavy chain variable region exon is excluded via a cassette-type alternative splicing mechanism. Southern blot analysis of the rearranged Ig heavy chain genes in one B cell line confirmed that the co-expressed mu+- and mu'-mRNA derive from the same rearranged Ig heavy chain gene. mu'-cDNA clones were readily isolated from normal human bone marrow lymphocytes, whereas peripheral B cells do not appear to express mu'-transcripts. The frequent occurrence of mu'-mRNA in B cell lines, and its high relative expression in untransformed bone marrow lymphocytes attest to a mode of post-transcriptional control of Ig gene expression that may have implications for human B cell development.

B-Lymphocytes↗
PubMed1990

VH and VL region structure of antibodies that recognize the (NANP)3 dodecapeptide sequence in the circumsporozoite protein of Plasmodium falciparum.

The sporozoite form of Plasmodium falciparum displays on its surface the circumsporozoite (CS) protein. The central domain of this protein possesses a reiterated tetrapeptide sequence Asn-Ala-Asn-Pro (NANP), and greater than 90% of the sporozoite-specific antibodies obtained from individuals living in malaria endemic areas recognize epitopes within this repeat sequence. Considering the highly repetitive structure of this naturally occurring antigen and its immunodominance, we were interested in analyzing the structural diversity of antibodies that bind to the (NANP)3 sequence. Molecular characterization of immunoglobulin heavy and light chain mRNA was performed for five hybridomas that produce antibodies with binding specificity for the dodecapeptide (NANP)3. These hybridomas were produced in BALB/c mice by inoculation with whole P. falciparum sporozoites. Sequence analysis and Northern blotting showed that for heavy chain, three hybridomas used VH elements that belong to the VHIX family and two to the VHJ558 family. Four different V kappa subgroups were represented among the light chains. Different D and J kappa segments are also utilized, while four heavy chain gene rearrangements involved the JH4 segment. These results indicated that multiple VH-VL gene combinations can code for reactivity to the (NANP)3 sequence, demonstrating that the murine antibody response to this immunodominant region is structurally heterogeneous.

Amino Acid Sequence↗
PubMed1989

Clonal diversity in the B cell repertoire of patients with X-linked agammaglobulinemia.

Ig protein and mRNA expression was examined in a collection of 18 monoclonal EBV-transformed B cell lines derived from five patients with X-linked agammaglobulinemia (XLA). A diversity of H and L chain isotypes were synthesized by these lines: the majority (12 lines) expressed mu kappa chains, while mu lambda (two lines), gamma kappa (one), gamma lambda (one), delta lambda (one), and alpha kappa (one) isotype expression was also observed. For all the mu kappa-producing XLA B cell lines, the mu and kappa mRNA transcripts were of native size, and sequence analysis across the regions of VHDJH and V kappa J kappa gene joining showed that Ig gene rearrangements occurred in a typical manner. A variety of VHDJH and V kappa J kappa gene rearrangements were observed, not only within the set of mu kappa+ XLA B cells as a whole, but also among the cell lines derived from single patients. Southern blot analysis for genomic Ig H chain gene rearrangements was done to fully assess the extent of clonal heterogeneity among multiple mu kappa+ XLA B cell lines derived from two patients; all the B cell lines possessed distinct gene rearrangement patterns demonstrating their clonal unrelatedness. Our findings indicate that the B cell repertoire in individual XLA patients is clonally diverse and that it is unlikely that the defect in B cell differentiation in XLA is the result of inefficient or ineffective rearrangement of Ig H or L chain genes. Rather, this study provides support for the idea that the XLA defect relates to a more generalized cellular function, such as regulating the proliferation and/or clonal expansion of cells of the B lymphoid lineage.

Adolescent↗
PubMed1989

Characterization of immunoglobulin mRNA expression in Burkitt lymphoma cell lines.

Immunoglobulin heavy- and light-chain mRNA of 11 Burkitt lymphoma (BL) cell lines (9 African and 2 American) were analyzed for various structural characteristics. In agreement with previous results at the protein level, all the BL cell lines express heavy-chain mRNA transcripts of the mu class. Surprisingly, a high mu s/mu m mRNA ratio was found in 2 IgM-producing BL cell lines (Raji and CCL85), that do not secrete immunoglobulin. Variable region gene use was also assessed in the cell lines: while 4 out of 7 endemic BL cell lines use VH genes that belong to the VH3 gene family, no clear bias in the expression of particular VH or VL gene families among this sampling of BL lines was found. Northern blot analysis of immunoglobulin transcripts in endemic BL cell lines did show that 2 such lines (AG876 and HTB62) expressed truncated heavy-chain transcripts; RNA sequence analysis of the VH region demonstrated different abnormal 5'-localized RNA splicing events for the 2 shortened mu transcripts. The light-chain mRNA in these 2 cell lines also showed structural abnormalities and, in the case of HTB62, 3 different kappa light-chain transcripts are produced (of elongated, native and truncated sizes). In vitro translation of mRNA from HTB62 showed mu and kappa chain proteins corresponding with the relative size for each message.

Amino Acid Sequence↗
PubMed1987

Molecular basis of the cell-surface expression of immunoglobulin mu chain without light chain in human B lymphocytes.

Four distinct human B-lymphoid cell lines possess the ability to circumvent the mechanism regulating intracellular transport of immunoglobulin protein. These cells do not produce light chains, yet they express mu heavy chains on the cell surface at comparable levels to B-cell lines that produce native forms of both proteins. The mu-chain mRNA produced in all four cell lines was found to contain an identical deletion of most of the heavy-chain variable (VH) region (75% of the 3' portion), with no apparent alteration in constant (C) region structure. The truncated mu (mu*)-chain mRNA in these cells was created through the use of a cryptic splice donor site found within the human VH gene(s) utilized by these B-cell lines. The truncated mu chains exhibited a decreased ability to associate with the intracellular transport regulatory protein, heavy-chain binding protein (BiP). This result indicates that VH region structure, in addition to C mu 1 region structure, influences the formation of the BiP recognition site on the heavy chain. Furthermore, it suggests that the mechanism allowing for cell-surface expression of the mu* chains in the absence of light-chain pairing is the inability of BiP to bind to the mu* chains and hence prevent their intracellular transport. The high frequency with which the mu-only surface immunoglobulin positive phenotype is present in our collection of human B-cell lines and the isolation of one of the cell lines from a healthy individual also suggest that B cells of this type may represent a significant subpopulation among the normal human B-cell repertoire.

B-Lymphocytes↗
PubMed1985

Treatment of oocyte membranes with the 2',3'-dialdehyde of guanosine triphosphate reduces progesterone inhibition of adenylyl cyclase.

Treatment of Xenopus laevis membranes with the 2',3'-dialdehyde of GTP (dial GTP) drastically inhibits their adenylyl cyclase activity. Optimal inhibition is obtained by treatment with 1 mM dial GTP for 1h at 32 degrees C. Using guanyl-5'-yl imidodiphosphate, F-, forskolin and Mn2+ as activators of the enzyme it can be concluded that dial GTP preferentially reacts with the stimulatory subunit (Ns) and slightly with the catalytic subunit. Dial GTP treatment greatly reduces the inhibition of adenylyl cyclase by progesterone. Pure exogenous Ns stimulates the enzyme but does not restore progesterone inhibition. Treatment with dial [alpha-32P]GTP labels several membrane proteins some of which have similar Mr to Ns and Ni.

Adenylyl Cyclase Inhibitors↗
PubMed1979

Cell growth in the monocular segment of the lateral geniculate nucleus following the opening or closing of one eye.

Both eyes were closed in 12 kittens soon after birth, and one eye was reopened at 23 days. From 14 to 26 days later, the cells in the monocular segment of the LGN connected to the open eye became significantly larger than the corresponding cells on the other side of the brain that were connected to the eye that was still closed. Up to 26 days after eye opening, the response of the monocular segment was similar to that of the binocular segment, so the latter may not be dependent on mutual inhibition or competition between sets of cells connected to each eye. From 30 to 60 days after eye opening, however, there were no differences between the monocular segments, but marked differences between the binocular A laminae where mutual inhibition and competition can occur. In seven more kittens both eyes were untouched until 23 days, when one eye was closed. Between 3 and 31 days later the deprived cells in the monocular segment of the LGN were not more than 8% smaller than those on the other side of the brain, and the measurements were not significantly different in any one cat. Within the binocular part of lamina A, cell growth is retarded by eye closure in two phases. Neither the early phase from 4--6 days nor the later phase from 21 days onwards occurred in the monocular segment, so both may be dependent on mutual inhibition of competition between the sets of cells connected to each eye. Two possible explanations of this difference between the effects of eye opening and eye closing are discussed.

Animals↗
PubMed1976

The effect of age on the reversibility of cellular atrophy in the LGN of the cat following monocular deprivation: a test of two hypotheses about cell growth.

Monocular closure soon after birth is known to reduce the growth of the deprived cells in the LGN provided that there are competing cells with normal input. When the closed eye was opened and the open eye closed after three of six weeks of monocular closure, the originally deprived cells in the LGN were able to recover their normal size. However, it was found that after 14 weeks of monocular closure there was no recovery. The ability of the initially closed eye to excite cells in the visual cortex is known to depend on the age when eye closure is reversed in a similar manner. Thus the growth of cells in the LGN is correlated with the possession of effective synapses upon cortical cells. This result is compatible with the possession of effective synapses upon cortical cells. This result is compatible with the hypothesis that competition occurs at the cortical level. It is argued that the alternative hypothesis of competition within the LGN predicts reversibility at any age. In some kittens, the closed eye was opened and the opposite optic nerve crushed. Some evidence was then found of structural recovery even after 14 weeks of deprivation. The hypothesis of cortical competition predicts functional recovery in such kittens, but this remains to be tested.

Age Factors↗
PubMed1976

Behavioral, biochemical and histological effects of prenatal administration of progesterone in the rat.

Pregnant Wistar rats were injected with progesterone (1.5 mg/kg) between Days 8 and 21 of gestation and the behavioral, biochemical and histological effects of this treatment were observed in the offspring. The progesterone offspring weighed less than the control animals during this weaning and were retarded on one measure of exploratory activity in the open field. None of the other 29 tests used showed any significant difference apart from a 9% increase in the amount of brain DNA in the progesterone animals. It was concluded that these differences were fortuitous and that progesterone has no consistent or significant effects on brain development in rodents following prenatal administration.

Animals↗