Genome Size and Karyotype Studies in Five Species of Lantana (Verbenaceae)

Lantana species are an important component of the U.S. environmental horticulture industry. The most commonly produced and used species are L. camara and, on a smaller scale, L. montevidensis. Both were introduced to the United States from Central and/or South America. Lantana species native to the continental United States include L. canescens, L. depressa, L. involucrata, etc. and most of them have not been well exploited. This study was conducted to obtain information about somatic chromosome numbers, karyotypes, and genome size of these five species. Nuclear DNA content in these species ranged from 2.74 pg/2C (L. involucrata) to 6.29 pg/2C (L. depressa var. depressa). Four chromosome numbers were observed: 2n = 2x = 22 in L. camara ‘Lola’ and ‘Denholm White’, 2n = 4x = 44 in L. depressa var. depressa, 2n = 2x = 24 in L. canescens and L. involucrata, and 2n = 3x = 36 in L. montevidensis. Two basic chromosome numbers were observed: x = 11 in L. camara and L. depressa var. depressa, and x = 12 in L. canescens, L. involucrata, and L. montevidensis. Analysis of somatic metaphases resulted in formulas of 20m + 2sm for L. camara ‘Lola’ and ‘Denholm White’, 12m + 12sm for L. canescens, 44m for L. depressa var. depressa, 10m + 14sm for L. involucrata, and 32m + 4sm for L. montevidensis. Satellites were identified in all five species, but were associated with a different chromosome group in different species. L. depressa var. depressa had the longest total chromatin length (146.78 µm) with a range of 1.88 to 4.41 µm for individual chromosomes. The maximum arm ratio was observed in L. canescens, with a ratio of 2.5 in chromosome group 3. L. depressa var. depressa was the only species that had all of its centromeres located in the median region of the chromosome. The results show significant differences in nuclear DNA content, chromosome number, and karyotype among three native and two introduced lantana species and will help to identify, preserve, protect, and use native lantana species. The information will be helpful in assessing the ploidy levels in the genus by flow cytometry.

Bất thường nhiễm sắc thể và liên quan tới kết quả điều trị sớm lơ xê mi cấp dòng lympho trẻ em tại Viện Huyết học - Truyền máu Trung ương giai đoạn 2016 - 2019

Cytogenetic variables in pediatric acute lymphoblastic leukemia (ALL) plays an important role in prognosis and risk grouping. Evaluation of early result treatment based on cytogenetic mutations provides data for physicians in treatment options for pediatric patients. Objectives: Study on characteristics of chromosomal abnormalities and evaluate the relationship with the early result of treatment according to FRALLE 2000 protocol at the National Institute of Hematology and Blood Transfusion. Subjects and research methods: This was a prospective study conducted on 188 pediatric ALL patients who were treated at the National Institute of Hematology and Blood Transfusion from August 1, 2016 to August 1, 2019. Results: The incidence of chromosomal abnormalities in pediatric ALL patients was 13.8%. Structural abnormalities were more common (57.7% of structural abnormalities alone, 15.4% combined with structural and numberal abnormalities, 26.9% of numberal abnormalities alone). The most common structural abnormality was chromosomal translocations, in which t(9;22) was the most common. Hyperdiploid accounted 90.9% in the abnormal number of chromosomes. The poor prognosis group accounted for a higher proportion in the study. The good prognosis chromosome group had the best treatment results (Overal Survival - OS 12 months reached 100%, Event Free Survival - EFS 12 months reached 80.0 ± 17.9%). The group with the poor prognosis of chromosome: OS 12 was only 66.0 ± 11.3%, EFS 49.4 ± 12.2%. The difference was statistically significant with p <0.01. The normal chromosome group had good OS and EFS for 12 months, 90.4 ± 2.6% and 77.9 ± 3.6%, respectively. Conclusion: The rate of abnormalities chromosome was low. Structural mutations were more common. Hyperdiploid was mainly seen on numberal chromosome abnormalities. This study found the difference in survival time between the groups according to the chromosome prognosis.

The RAD51 gene family in bread wheat is highly conserved across eukaryotes, with RAD51A upregulated during early meiosis

The RADiation sensitive protein 51 (RAD51) recombinase is a eukaryotic homologue of the bacterial Recombinase A (RecA). It is required for homologous recombination of DNA during meiosis where it plays a role in processes such as homology searching and strand invasion. RAD51 is well conserved in eukaryotes with as many as four paralogues identified in vertebrates and some higher plants. Here we report the isolation and preliminary characterisation of four RAD51 gene family members in hexaploid (bread) wheat (Triticum aestivum L.). RAD51A1, RAD51A2 and RAD51D were located on chromosome group 7, and RAD51C was on chromosome group 2. Q-PCR gene expression profiling revealed that RAD51A1 was upregulated during meiosis with lower expression levels seen in mitotic tissue, and bioinformatics analysis demonstrated the evolutionary linkages of this gene family to other eukaryotic RAD51 sequences. Western blot analysis of heterologously expressed RAD51 from bread wheat has shown that it is detectable using anti-human RAD51 antibodies and that molecular modelling of the same protein revealed structural conservation when compared with yeast, human, Arabidopsis and maize RAD51A orthologues. This report has widened the knowledge base of this important protein family in plants, and highlighted the high level of structural conservation among RAD51 proteins from various species.