Serological and genotyping study of rare cis-AB01/O01 in the area of Inner Mongolia - with a case report

The antigen gene of ABO blood group system, called ABO, is located on human chromosome 9, with a total length of 19.5 kb. It is the first blood group system found by human beings.[1] ABO blood group subtypes are formed by ABO genovariation, i.e., gene A variation for A subtype, gene B variation for B subtype and gene O variation for new O alleles. ABO subtypes contain A3, Ax, Ael, Aw, Am, B3, Bx, Bel, Bw, cis-AB, B (A). Generally, an individual with AB blood group has an A allele on one chromosome, with B allele on its paired chromosome. This phenomenon is called trans-AB. However, cis-AB is a unique ABO phenotype that A and B alleles are located on the same chromosome, so that it can be inherited by the next generation.[2] This special mode of inheritance often causes a discrepancy of ABO blood grouping and then reduces the effectiveness and safety of blood transfusion.Therefore, to accurately identify the blood group of cis-AB is a precondition for the safety of blood transfusion.[3] The serological and genotyping analysis on a case of cis-AB patient in our hospital is reported as follows.

SYCE2 is required for synaptonemal complex assembly, double strand break repair, and homologous recombination

Synapsis is the process by which paired chromosome homologues closely associate in meiosis before crossover. In the synaptonemal complex (SC), axial elements of each homologue connect through molecules of SYCP1 to the central element, which contains the proteins SYCE1 and -2. We have derived mice lacking SYCE2 protein, producing males and females in which meiotic chromosomes align and axes form but do not synapse. Sex chromosomes are unaligned, not forming a sex body. Additionally, markers of DNA breakage and repair are retained on the axes, and crossover is impaired, culminating in both males and females failing to produce gametes. We show that SC formation can initiate at sites of SYCE1/SYCP1 localization but that these points of initiation cannot be extended in the absence of SYCE2. SC assembly is thus dependent on SYCP1, SYCE1, and SYCE2. We provide a model to explain this based on protein–protein interactions.

A family of complex tandem DNA repeats in the telomeres of Chironomus pallidivittatus

A family of 340-bp tandem telomere-associated DNA repeats is present in 50- to 200-kb blocks in seven of the eight paired chromosome ends in Chironomus pallidivittatus. It consists of four main subfamilies, differing from each other by small clusters of mutations. This differentiation may reflect different functional roles for the repeats. Here we find that one subfamily, D3, is consistently localized most peripherally and extends close to the ends of the chromosomes, as shown by its sensitivity to the exonuclease Bal 31. The amounts of D3 are highly variable between individuals. The repeat characteristic for D3 forms a segment with pronounced dyad symmetry, which in single-strand form would give rise to a hairpin. Evidence from an interspecies comparison suggests that a similar structure is the result of selective forces. Another subfamily, M1, is present more proximally in a subgroup of telomeres characterized by a special kind of repeat variability. Thus, a complex block with three kinds of subfamilies may occupy different M1 telomeres depending on the stock of animals. We conclude that subfamilies are differentially distributed between and within telomeres and are likely to serve different functions.

A family of complex tandem DNA repeats in the telomeres of Chironomus pallidivittatus.

A family of 340-bp tandem telomere-associated DNA repeats is present in 50- to 200-kb blocks in seven of the eight paired chromosome ends in Chironomus pallidivittatus. It consists of four main subfamilies, differing from each other by small clusters of mutations. This differentiation may reflect different functional roles for the repeats. Here we find that one subfamily, D3, is consistently localized most peripherally and extends close to the ends of the chromosomes, as shown by its sensitivity to the exonuclease Bal 31. The amounts of D3 are highly variable between individuals. The repeat characteristic for D3 forms a segment with pronounced dyad symmetry, which in single-strand form would give rise to a hairpin. Evidence from an interspecies comparison suggests that a similar structure is the result of selective forces. Another subfamily, M1, is present more proximally in a subgroup of telomeres characterized by a special kind of repeat variability. Thus, a complex block with three kinds of subfamilies may occupy different M1 telomeres depending on the stock of animals. We conclude that subfamilies are differentially distributed between and within telomeres and are likely to serve different functions.

Morphology and genome analyses of interspecific hybrids of Elymus scabrus

Sexual, hexaploid (2n = 42) Elymus scabrus (R. Br.) A. Löve (formerly Agropyron scabrum (R. Br.) Beauv.) was used as the male parent for crossability studies and genome analysis of this Australian species. Mean number of paired chromosome arms (PA) and mean number of chromosome associations per metaphase I cell were determined for four different interspecific hybrids. Means by the female parent of each interspecific hybrid were as follows: tetraploid Elymus canadensis L., 1.17 PA and 32.76 I + 0.04 II (ring) + 1.08 II (rod) + 0.005 IV (chain) in 179 cells from four F1's; hexaploid Elymus tsukushiensis Honda, 14.13 PA and 23.48 I + 4.69 II (ring) + 4.13 II (rod) + 0.27 III + 0.01 IV (ring) + 0.01 IV (rod) in 140 cells from three F1's; tetraploid Elymus longearistatus (Boiss.) Tzvelev, 4.20 PA and 27.53 I + 0.39 II (ring) + 3.12 II (rod) + 0.15 III in 59 cells from one F1; and tetraploid Elymus semicostatus (Nees ex Steud.) A. Löve, 3.98 PA and 27.961 + 0.34 II (ring) + 2.86 II (rod) + 0.16 III + 0.04 IV (chain) in 50 cells from one F1. All F1's were completely sterile. An amphiploid of F1 E. tsukushiensis – E. scabrus was obtained by 0.1% colchicine treatment. It was partially sterile and had the expected chromosome number of 2n = ca. 84. The data were interpreted to indicate that E. scabrus lacks the S and H genomes of E. canadensis, contains the Y genome and a modification of another genome of E. tsukushiensis, and a modification of the Y genomes of E. longearistatus and E. semicostatus. These results contradict a previous report of an S and H genome composition for the Australasian wheatgrasses. Key words: apomixis, Elymus canadensis, Elymus longearistatus, Elymus semicostatus, Elymus tsukushiensis.

THE EFFECT OF WHEAT CYTOPLASM ON MEIOSIS OF HEXAPLOID TRITICALE

The interrelationships among source of cytoplasm, chromosome pairing and the duration of meiosis were studied in eight combinations of hexaploid triticale (× Triticosecale Wittmack) grown at 20 °C under continuous illumination. The number of paired chromosome arms and univalents per pollen mother cell at MI ranged from 32.32 and 4.89 to 37.26 and 1.37, respectively. Meiosis lasted from 44.14 to 49.35 hours. A significant positive correlation (r = 0.92) was found between total duration of meiosis and the combined duration of zygotene and pachytene, the stages during which chromosome pairing is thought to occur. The origin of the cytoplasm (from tetraploid or hexaploid wheat) had no significant effect of chromosome pairing or meiotic duration. No relationship was found between total duration of meiosis, or that of zygotene and pachytene, and chromosome pairing. It was concluded that lack of sufficient time for homologues to pair cannot account for the presence of rye chromosomes as univalents in triticaie.

GENOTYPIC AND CYTOLOGICAL INFLUENCES ON THE MEIOSIS OF HEXAPLOID TRITICALE

Two groups of hexaploid triticale were synthesized from the crosses of two cultivars of diploid rye (Secale cereale L.) with (a): two cultivars of tetraploid macaroni wheat (durum-group of Triticum turgidum L.), and (b): extracted AABB tetraploids of three cultivars of hexaploid bread wheat (T. aestivum L. em. Thell.).The extracted triticales, as a group, showed the greater chromosome regularity in the division of their PMC's. This was attributed to the prior adaptation of the extracted AABB component to the hexaploid meiosis of bread wheat. There was much variation in chromosome behaviour among triticales which had in common the same parental cultivars of wheat and rye. This genetic variability most likely came from the heterogeneity of gametes that were contributed by the two outbred cultivars of rye.AI was delayed in PMC's in which there was a low level of synapsis at MI. This effect was related to the total number of chromosome arms that were paired in each cell (arm pairs), regardless of how many univalents each cell contained. Non-randomness in the distribution of paired chromosome arms suggested that some chromosomes (possibly derived from rye) were less likely to pair than others.The rate at which univalents were formed in cells with a particular number of arm pairs was clearly influenced both by the genotype and by the environment of the triticale in question.