Molecular genotyping of the HLA-DQ α gene region

Restriction fragment analysis has been applied to genomic DNA extracted from human tumor cell lines. Polymorphic restriction fragments encompassing the HLA-DQ gene were observed upon digestion with Bgl II, Eco RI, and Hind III. Analysis of these polymorphic fragments (or allogenotopes) showed that for each restriction enzyme a series of three differently sized allogenotopes existed. Clusters of cosegregating allogenotopes belonging to the different allelic series defined three different allogenotypes. Each allogenotype exhibited a distinctive restriction map generated by digestion with five restriction enzymes. Comparison of these restriction maps showed that generation of the polymorphisms observed at the HLA-DQ region in these sets of cell lines is not caused by a single event. In some B- and T-lymphoma cell lines a fourth allogenotype was found. The restriction site map of genomic DNA from these cell lines suggested that the latter distribution of restriction enzyme sites was most probably generated by recombination between two of the previously observed allogenotypes at a crossover site(s) adjacent to the HLA-DQ gene.     

A polymorphic region defined by pCN2 (the 3′ nontranslated region of N-ras) maps to chromosome 9cen-p12

Summary Abnormalities of chromosome 9p have been reported in human leukemias and lymphomas, and in cell lines lacking the enzyme methylthioadenosine phosphorylase. It has been shown pCN2, the 3 nontranslated region of the N-ras oncogene, crosshybridizes with unknown DNA segments on chromosome 6, 9p, and 22, in addition to the N-ras oncogene itself on chromosome 1p. To use pCN2 to study chromosome 9p abnormalities in malignancies, we undertook to localize the pCN2 crosshybridizing region in chromosome 9p. By analyzing the copy numbers of the pCN2 crosshybridizing bands associated with chromosome 9p among various chromosomally aberrant human cell lines, we mapped the pCN2 hybridizing region to 9cen-p12. Since there is no other available probe in this region, pCN2 should prove very useful in studying abnormalities of chromosome 9p in human malignancies.This is publication number 5969-MEM from the Research Institute of Scripps Clinic, La Jolla, California     

Heavy chain variable region contribution to the NPb family of antibodies: somatic mutation evident in a γ2a variable region

To examine germ line genes of the heavy chain variable region (V_H) that might contribute to formation of antibodies of the NP^b family, we have derived cDNA clones from two hybridomas making NP^b antibodies. One, B1–8, made an IgM protein and was derived during a primary response; the other, S43, made an IgG_2a protein and was derived during a hyperimmune response. Sequence comparison of the two clones showed that they differed by only 10 bp in the V_H region, had very different D segments and had identical J segments (J₂). A set of closely related germ line V_H genes was then cloned from a partial Eco RI library of C57BI/6 DNA. By comparing the germ line V_H regions to the cDNA V_H regions, we identified seven potential candidates for encoding the V_H regions of NP^b antibodies. The seven V_H regions were sequenced, and one V(186-2) contained exactly the DNA sequence found in the clone derived from B1–8. None of the DNA sequence differences that distinguished the S43-derived clone from the B1–8 clone was found in any of the other six germ line genes. Because the S43 sequence was more closely related to the V(186-2) germ line sequence than to any of the other V_H genes, we conclude that the differences between the genes resulted from somatic mutation and that the two hybridomas derived their V_H regions from the same germ line gene. Certain of the sequenced V_H genes contain crippling mutations; the repertoire of germ line V_H genes that can contribute to the diversity of antibodies may therefore be less than the total number of genes detectable by hybridization.     

Gorski Kotar--an endemic region for primary gastric non-hodgkin lymphoma?

Primary gastric non Hodgkin lymphoma (PGNHL) is a distinct group of extranodal lymphomas with interesting geographical distribution and variable prevalence in different countries. We analysed epidemiological data of our patients with PGNHL in Primorsko-goranska County. Clinical data of 30 patients with PGNHL diagnosed and treated in Clinical Hospital Center of Rijeka, Croatia between January 1995 and December 2005 were prospectively analyzed. We used statistical analysis (t-test, chi2-test) for small groups. Out of 30 pts with PGNHL, 19 were born in Primorsko-goranska County, part of Croatia situated by the Adriatic sea which consists of three regions: City of Rijeka, Islands and Gorski Kotar. 6 of 19 patients (31.6%) were originally from Gorski Kotar which made incidence rate of PGNHL in Gorski Kotar 7 times higher than in other two regions. Many authors emphasized that relative frequency of PGNHL is very variable in various countries and regions. Geographical distribution of our patients was very surprising because Gorski Kotar is the region with lowest number of citizens, rural area without any known pollutants, and ecologically one of the most preserved microsystem in this part of Croatia. Gorski Kotar is known to be an endemic region for multiple sclerosis and lyme borreliosis. Is it for PGNHL too?     

A new mouse T-cell receptorα chain variable region family

Sequence analysis of the rearranged T-cell receptor a chain gene segments from an influenza reactive T-cell clone T2.5-5 and a hemin chloride reactive T-cell hybrid SJL-HE-1.1 have revealed a previously undescribedV gene family. We have designated this familyV 15. Southern hybridization analysis has indicated that this family most probably contains only two members, and that these are conserved in each of six mouse strains representing three previously describedV haplotypes:V ^a ,V ^b , andV ^c .     

Polymorphic tandem repeat region in interleukin-1α intron 6

Analysis of polymerase chain reaction amplified products from the sixth intron of the human interleukin-1 gene reveals a high polymorphism (polymorphism information content = 0.51) in a Caucasian population. Altogether, seven alleles have been defined ranging from 620 to 1220bp. This polymorphism is probably attributable to a variable number of 46-bp tandem repeats, each containing potential regulatory sequences.     

Strand symmetry of mutation rates in theβ-globin region

Summary It has been suggested that there may be inequalities in the types of substitution on the two DNA strands (in particular, in the frequencies of transversions from R to Y and from Y to R) due to a higher error rate on the lagging than the leading strand during replication. Reexamination of 11 kb of the -globin region sequenced in six primates fails to confirm this suggestion. Examination of the 73-kb -globin region sequenced in humans shows that the frequency of pyrimidines in different parts of this region is more variable than expected in a random sequence, but the pattern is more consistent with nonrandomness generated by DNA turnover mechanisms than with strand asymmetry due to a higher error rate on the lagging strand.     

Is a differentiated advice by season and region necessary?

The ultraviolet radiation component in the solar spectrum varies greatly with season. In the summer, the significant short-wavelength (UV-B) radiation at midday can produce erythema in sensitive skin in less than 20 min in middle latitudes, and yet in winter months, the same midday exposure dose would require hours of exposure. The challenge for public health authorities is to provide simple, understandable messages for sensitive individuals to limit excessive exposure at appropriate times of the day during spring and summer months and yet not to take needless precautions or limit exposure during fall and winter months at mid and circumpolar latitudes. The appropriate exposure for beneficial effects is not possible to achieve at many latitudes during winter months, but is readily achieved in summer months. Simple messages should be tailored to the local times of day, reflecting the locale and season. One simple means to communicate the relative UV-B exposure relates to the length of one's shadow (the "Shadow Rule"). Further challenges are presented when apparently mixed messages would be justified for different skin phototypes.     

α-MSH injected into the septal region reduces fever in rabbits

In previous research the concentration of α-MSH within the septal region of rabbits increased with fever. This finding raises the possibility that the septal concentration of this peptide, which reduces fever when given both peripherally and intracerebroventricularly, is important to limitation of fever. To test this idea, rabbits with cannulas in the septal region were made febrile by IV injections of leukocytic pyrogen (LP). Injection of α-MSH (1 μg bilaterally) into the septal region did reduce fever, consistent with the idea that the increase in septal α-MSH concentration which occurs naturally in fever limits the febrile response. We also noted late rises in body temperature when experimental and control septal injections were given close together in time. These increases in temperature were similar to those known to occur after injections into the primary temperature control in the PO/AH region. This commonality further strengthens the possibility that septal neurons are important to central modulation of body temperature.     

Cloning and characterization of the immunity region of phage ?80

Summary The immunity region of phage 80 has been localized. It codes for at least three proteins: a protein of 34 kDa which has the biological properties of the phage repressor, and two other proteins of 9 kDa and 18 kDa which are the first proteins on the rightward operon. These two proteins are negatively regulated by the 34 kDa protein at a divergent promoter site. By position analogy with phage , but not by its biological activity, the 9 kDa protein could be the cro roduct. The 18 kDa protein is able to block totally UV induction of phage 80.     

Two closely related κ variable region pseudogenes pose an evolutionary paradox

Two pseudogenes belonging to the Igk-V1 variable region group have been isolated from BALB/c mice. The genes share >96.5% identity of nucleotide sequence in a 1800 base pair (bp) region surrounding the coding region, but deletions of 221 bp and 84 bp have removed essential sequences from the two genes. As the deletions are different in the two pseudogenes, they must have occurred independently in each gene during or subsequent to the duplication event which gave rise to the genes from a common ancestral gene. Polymerase chain reaction analysis was used to identify the pseudogenes in inbred strains of mice. BALB/c (Igk ^c) and AKR (Igk ^a), prototype strains representative of the predominant haplotypes, possess both pseudogenes but no intact copy. Only one of the pseudogenes was present in SJL (Igk ^a). Strains C58, c.C58 (Igk ^d) and NZB (Igk ^b) possessed an intact version of the gene. This distribution of haplotypes is consistent with a close linkage of the pseudogenes with other Igk-V1 genes on chromosome 6. The translated amino acid sequence of the pseudogenes indicates that prior to their acquiring deletions they encoded typical Igk-V1 variable regions except for an unusual FR2 region, in which the conserved proline at position 44 is replaced by leucine and the normally hydrophobic position 36 was occupied by histidine. Possible mechanisms to explain the occurrence of deletions in both of the pseudogenes in the recent evolution of BALB/c are discussed. One explanation would be that the two genes were already nonfunctional at the time of the duplication so that the subsequent deletions represent neutral events which became fixed in the inbred strains by a process of genetic drift. Alternatively, if the genes were functional at the time of duplication, their rapid loss due to deletion events suggests that negative selection may have acted to eliminate the genes from the V-region repertoire. Address correspondence and offprint requests to: D. M. Gibson.