Molecular Genetic Data Research Articles

Getah Virus (Alphavirus): An Emerging, Spreading Zoonotic Virus.

Getah virus (GETV) is a zoonotic virus transmitted by mosquitoes, belonging to the Togaviridae family, Alphavirus genus. It was first isolated from mosquitoes in Malaysia in 1955, being widespread in island countries in the South Pacific region. Since the beginning of the 21st century, GETV expanded its range and geographical distribution from low-latitude tropical regions to 60° north latitude, being isolated from 17 different species of mosquitoes belonging to five genera of Culicidae (Culex, Anopheles, Armigeres, Aedes and Mansonia), as well as from midges in Eurasia. Molecular genetic evolution analysis revealed large molecular differences between the mosquitoes currently circulating Eurasia and those in the South Pacific in 1950s. The number of disease outbreaks caused by GETV in animals is increasing alongside the types of animals infected, from horses and pigs to cattle, blue foxes and red pandas. The disease burden is severely underestimated, and the economic cost to livestock production remains unknown. Herein, we review GETV temporal and spatial distribution, molecular genetic evolution, transmission and data on disease outbreaks. This work provides a reference for public health workers engaged in GETV research and zoonotic disease prevention and control.

The molecular genetics of human appendicular skeleton.

Disorders that result from de-arrangement of growth, development and/or differentiation of the appendages (limbs and digit) are collectively called as inherited abnormalities of human appendicular skeleton. The bones of appendicular skeleton have central role in locomotion and movement. The different types of appendicular skeletal abnormalities are well described in the report of "Nosology and Classification of Genetic skeletal disorders: 2019 Revision". In the current article, we intend to present the embryology, developmental pathways, disorders and the molecular genetics of the appendicular skeletal malformations. We mainly focused on the polydactyly, syndactyly, brachydactyly, split-hand-foot malformation and clubfoot disorders. To our knowledge, only nine genes of polydactyly, five genes of split-hand-foot malformation, nine genes for syndactyly, eight genes for brachydactyly and only single gene for clubfoot have been identified to be involved in disease pathophysiology. The current molecular genetic data will help life sciences researchers working on the rare skeletal disorders. Moreover, the aim of present systematic review is to gather the published knowledge on molecular genetics of appendicular skeleton, which would help in genetic counseling and molecular diagnosis.

Comparative analysis of zooplankton diversity in freshwaters: What can we gain from metagenomic analysis?

AbstractMolecular genetic approaches applied to environmental DNA have great potential for biodiversity research and ecosystem monitoring. A metagenome is produced via shotgun sequencing of DNA collected directly from the environment and represents a sample of genetic information from all organisms captured in an environmental sample. Metagenomes have been primarily used to study bacteria and archaea, but promising reports focusing on metazoan diversity are emerging. However, methodological uncertainties remain, and studies are required to validate the power and the limitations of such an approach when applied to macro‐eukaryotes. Here, we analyzed water sample metagenomes to estimate zooplankton diversity in 22 freshwater lakes across eastern Canada. We tested the coherence of data based on field samples collected at the same time: 1) morphologically identified zooplankton specimens and 2) molecular genetic data derived from shotgun sequencing of environmental DNA for which we applied two different bioinformatic workflows: a whole metagenome mapping approach and a small subunit (SSU) rRNA gene prediction approach. We further evaluated diversity trends emerging from each dataset in relation to major environmental gradients. We found a significant correlation between the relative abundance of zooplankton families identified based on SSU rRNA gene prediction and morphology. However, differences in congruence between metagenomes and morphological identifications were detected when varied bioinformatic approaches were applied to the presence–absence data. This study presents one of the first diversity assessments of a group of aquatic metazoans using metagenomes and validates the coherence of the community composition derived from genomic and classical species surveys. Overall, our results suggest that metagenomics has the potential to be further developed to describe metazoan biodiversity in aquatic ecosystems, and to advance this area we provide key recommendations for workflow improvement.

A new species of black fly, formerly cytoform C of the Simulium angulistylum complex (Diptera: Simuliidae), from a high mountain in northeastern Thailand.

Cytoform C, one of three cytoforms in the Simulium angulistylum Takaoka & Davies complex from a high mountain in northeastern Thailand was morphologically and molecularly investigated. All known life stages (larva, pupa, adult male and female except egg) were morphologically similar to, but distinguishable from S. angulistylum s. str. and S. isanense Takaoka, Srisuka & Saeung in the adults by the relative length of the fore and hind basitarsi and relative length of the tooth to the claw. It is also morphologically distinct from other species of the S. epistum species-group. Here, it is formally described as a new species, S. prayooki. Molecular genetic data based on mitochondrial cytochrome c oxidase subunit I (COI) also supported the morphological similarity between the new species and the two related known species (S. angulistylum s. str. and S. isanense) as phylogenetic analysis retrieved them all from a single clade and with a low level of interspecific genetic divergence (1.74%). This might possibly have resulted from incomplete lineage sorting as they are likely to share a recent common ancestor. Despite limitation of molecular genetic differentiation, the new species was distinctly different from two other cytoforms of S. angulistylum complex based on polytene chromosome banding patterns and ecology of the immature stages. Thus, this study highlights the necessity of using an integrated approach for fully understanding black fly biodiversity.

Comprehensions keen on the biology of Brain tumors: Possibilities and Challenges

The word “tumor” is a Greek term that refers to a swelling or a lump. In modern medical terms, a tumor is usually an abnormal mass of cells and tissues, which grows due to the abnormal division of cells. The unnatural division of cells occurs due to the cancerous nature of these cells, which no longer obey standard checkpoints that prevent healthy or non-cancerous cells from uncontrolled cell divisions. Tumors may be circumscribed or diffuse depending on whether they remain localized to a part of the brain or spread to other parts aggressively by metastasis; in 2016, WHO has classified tumors of the brain or central nervous system by taking into account the latest molecular genetic data along with classic histopathological features characteristic of each kind of tumor. The new classification system makes diagnosis more precise, but a better analysis of prognosis is now possible since genotype is far more determinative and accurate than histological phenotype. Modern technologies like high throughput gene sequencing, CRISPR-Cas9 gene editing, and personalized medicine approaches have improved the prognosis of brain tumor patients. They have also revolutionized our understanding of the biology of brain tumors and how they are now being treated. In this review, we will discuss the latest knowledge about the biology of brain tumors and how modern technologies are helping to understand the molecular basis of these pathologies and develop better treatment options to improve patient survival.

Increased Late Noncardiac Nonrelapse Mortality in Patients with Atrial Fibrillation Diagnosed During Their Hospital Stay for Allogeneic Stem Cell Transplantation

Atrial fibrillation (AF) is the most common arrhythmia in adults but its impact on allogeneic stem cell transplantation (SCT) is not well characterized. We studied AF manifestation during the hospital stay for allogeneic SCT, referred to as AF in hospital (AFiH), and analyzed the incidence of, risk factors for, and clinical impact of AFiH on intensive care unit (ICU)-/hospital-/ and overall survival (OS), relapse-free survival (RFS), nonrelapse mortality (NRM), and graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS). This retrospective matched cohort study comprised 553 consecutive SCT recipients at Hannover Medical School between January 2013 and October 2019. Patients with AFiH were compared with a non-AFiH control cohort matched for Hematopoietic Stem Cell-Specific Comorbidity Index (HCT-CI), European Group for Blood and Marrow Transplantation (EBMT) risk score, disease, conditioning regimen and availability of molecular genetic data for patients with myeloid diseases. AFiH occurred in 46 patients (8%) at a median of 2 days (interquartile range, 0 to 8 days) after SCT. Patient history of AF and elevated NT-proBNP and high-sensitivity troponin T levels, but not conventional echocardiographic parameters, were predictive for AFiH. AFiH occurred more often in patients with mutations in DNMT3A, TET2, and ASXL1 genes related to clonal hematopoiesis compared with patients with wild-type alleles, with the greatest impact from DMT3A mutations. ICU admission was significantly higher in the AFiH cohort (46% versus 7%), without significant differences in ICU or post-ICU hospital survival (62% versus 40% and 52% versus 40%, respectively). The main cause of death was sepsis. In terms of long-term outcomes, the incidences of relapse and grade II-IV acute GVHD did not differ significantly between the AFiH and the non-AFiH groups; however, OS was significantly shorter in the AFiH group (1 year OS, 39% versus 65%), owing to late noncardiac NRM (1 year NRM, 49% versus 27%). Although the underlying cellular and molecular mechanisms remain to be characterized in further detail, these data clearly demonstrate the impact of inpatient AF manifestation/AFiH on long-term outcomes of SCT recipients.

Implementation of Gene Expression Profiles in the HL7 FHIR Standard.

Gene expression profiles can capture significant molecular differences paving the way toward precision medicine. However, clinical standards like FHIR only provide encoding of molecular sequence variations, even so, expression patterns are equally important for decision making. Here we provide an exemplary implementation of gene expression profiles of a microarray analysis using an adaption of the FHIR Genomics extension. Our results demonstrate how FHIR resources can be facilitated in bioinformatics-based decision support systems or used for the aggregation of molecular genetics data in multi-center clinical trials.

NMR-based metabolomic profiling can differentiate follicular lymphoma from benign lymph node tissues and may be predictive of outcome

Follicular lymphoma (FL) is a cancer of B-cells, representing the second most common type of non-Hodgkin lymphoma and typically diagnosed at advanced stage in older adults. In contrast to the wide range of available molecular genetic data, limited data relating the metabolomic features of follicular lymphoma are known. Metabolomics is a promising analytical approach employing metabolites (molecules < 1 kDa in size) as potential biomarkers in cancer research. In this pilot study, we performed proton nuclear magnetic resonance spectroscopy (1H-NMR) on 29 cases of FL and 11 control patient specimens. The resulting spectra were assessed by both unsupervised and supervised statistical methods. We report significantly discriminant metabolomic models of common metabolites distinguishing FL from control tissues. Within our FL case series, we also report discriminant metabolomic signatures predictive of progression-free survival.

Posterior probabilities of membership of repertoires in acoustic clades.

Recordings of calls may be used to assess population structure for acoustic species. This can be particularly effective if there are identity calls, produced nearly exclusively by just one population segment. The identity call method, IDcall, classifies calls into types using contaminated mixture models, and then clusters repertoires of calls into identity clades (potential population segments) using identity calls that are characteristic of the repertoires in each identity clade. We show how to calculate the Bayesian posterior probabilities that each repertoire is a member of each identity clade, and display this information as a stacked bar graph. This methodology (IDcallPP) is introduced using the output of IDcall but could easily be adapted to estimate posterior probabilities of clade membership when acoustic clades are delineated using other methods. This output is similar to that of the STRUCTURE software which uses molecular genetic data to assess population structure and has become a standard in conservation genetics. The technique introduced here should be a valuable asset to those who use acoustic data to address evolution, ecology, or conservation, and creates a methodological and conceptual bridge between geneticists and acousticians who aim to assess population structure.

Genetic Etiology of Neonatal Diabetes Mellitus in Vietnamese Infants and Characteristics of Those With INS Gene Mutations

BackgroundNeonatal diabetes mellitus (NDM) is a rare (1:90,000 newborns) but potentially devastating metabolic disorder characterized by hyperglycemia combined with low levels of insulin. Dominantly-acting insulin (INS) gene mutations cause permanent NDM through single amino acid changes in the protein sequence leading to protein misfolding, which is retained within the endoplasmic reticulum (ER), causing ER stress and β-cell apoptosis. Over 90 dominantly-acting INS gene mutations have been identified in individuals with permanent NDM.Patients and MethodsThe study included 70 infants diagnosed with NDM in the first year of life between May 2008 and May 2021 at the Vietnam National Children’s Hospital. Sequencing analysis of all the genes known to cause NDM was performed at the Exeter Genomic Laboratory, UK. Clinical characteristics, molecular genetics, and annual data relating to glycemic control (HbA1c) and severe hypoglycemia of those with INS mutations were collected. The main outcomes of interest were HbA1c, daily insulin dose, growth, and cognitive/motor development.ResultsFifty-five of 70 infants (78.5%) with NDM harbored a mutation in a known disease-causing gene and of these, 10 had six different de novo heterozygous INS mutations. Mean gestational age was 38.1 ± 2.5 weeks and mean birth weight was 2.8 ± 0.5 g. They presented with NDM at 20 ± 17 weeks of age; 6/10 had diabetic ketoacidosis with pH 7.13 ± 0.26; plasma glucose level 32.6 ± 14.3 mmol/l and HbA1C 81 ± 15% mmol/mol. After 5.5 ± 4.8 years of insulin treatment, 9/10 have normal development with a developmental quotient of 80-100% and HbA1C 64 ± 7.3 mmol/mol, 9/10 have normal height, weight, and BMI on follow-up.ConclusionsWe report a series of Vietnamese NDM cases with dominant INS mutations. INS mutations are the third commonest cause of permanent NDM. We recommend screening of the INS gene in all children diagnosed with diabetes in the first year of life.

DNA markers in oat breeding for crown rust resistance (a review)

Crown rust is the most harmful disease of oat (Avena sativa L.) around the world. The purpose of this review is to analyze and generalize the available information about DNA markers developed for oat breeding for resistance to crown rust. The review reveals the mechanisms of the A. sativa resistance to the fungus Puccinia coronata Corda f. sp. avenae Erikss. which causes crown rust disease. Special attention is paid to the race-specific resistance caused by the action of Pc genes and the nonspecific resistance controlled mainly by the loci of quantitative traits. Strategies for creating resistant genotypes and the role of molecular markers in oat breeding for crown rust resistance are discussed. Currently, research is focused mainly on the search for and development of molecular markers related to the oat race-specific resistance to P. coronata.The article presents the technological advantages and disadvantages of the existing DNA markers. KASP, TaqMan and HRM markers are currently the most promising technologies for identifying crown rust resistance genes. The validated SCAR and STS markers for the Pc39, Pc68, Pc91, Pc94 genes are recommended as the most available for implementation in practical oat breeding. The results of recent studies on identifying loci of nonspecific resistance to P. coronata are also presented. In general, the use of DNA markers has significant potential for creating oat genotypes resistant to crown rust under present-day conditions. DNA markers of various types are recommended for practical use, in particular for pyramiding genes and increasing the resistance period of new cultivars. Introduction of DNA markers into oat breeding will increase with the growth of molecular genetic data and the improvement of technologies for identifying genes and loci associated with both race-specific and nonspecific resistance of oat to P. coronata.

Cryopyrin-associated periodic syndrome assess the efficacy and safety of anakinra therapy: a single center experience

The aim of this study was to analyze the clinical, laboratory and molecular genetic data of 20 patients (9 boys, 11 girls) diagnosed with cryopyrin-associated periodic syndrome (CAPS) with an assessment of the efficacy and safety of therapy in 6 patients with an inhibitor of the interleukin-1 receptor – anakinra. The study was approved by the Independent Ethics Committee and the Scientific Council of the D. Rogachev NMRCPHOI. The patients' parents gave their consent to the use of their child's data, including photographs, for research purposes and in publications. The age of CAPS manifestation ranged from 0 to 27.0 months (median – 2 months). The clinical manifestations were dominated by fever, rash, lesions of the central nervous system, musculoskeletal system. During the attack, all 20 patients had an increase acute phase proteins of blood. All patients had heterozygous mutation in the NLRP3 gene, with the highest frequency of localization in exon 3 (17/20). 6/20 patients were initiated on anakinra therapy. All 6 patients who have been treated of anakinra enough to assess the effect of the treatment, drastic improvement of the condition was noted, but only in 5/6 patients achieved full remission.

Phylogenetic phytogeography of selected groups of seagrasses (Monocotylendoneae - Alismatales) based on analysing of genes 5.8S rRNA and RuBisCo large subunit

Seagrasses are representatives of the families Cymodoceaceae, Posidoniaceae, Zosteraceae, Hydrocharitaceae (Monocotylendoneae - Alismatales), adapted to growing in seawaters and all their important life circle events are taking place under the water including pollination and distribution of diasporas. Seagrasses are widespread in the littoral areas of the World Ocean, except for Antarctica, and play an important ecosystem role. Due to the insufficiently studied history of dispersal and formation of modern seagrasses habitats, we carried out a phylogenetic analysis of representatives of the families Cymodoceaceae (Amphibolis, Halodule, Syringodium, Cymodocea, and Thalassodendron), Posidoniaceae (Posidonia), Zosteraceae (Zostera, and Phyllospadix), and Hydrocharitaceae (Enhalus, Halophila, and Thalassia). The cladograms constructed based on molecular data analysis of the 5.8S ribosomal RNA and ribulose–1,5–bisphosphate carboxylase/oxygenase large subunit genes are used as the basis for reconstructing the history of dispersal of the studied taxa. It is found that the main stages of dispersal of selected groups of seagrasses took place in the Late Cretaceous period. The main track of historical distribution is largely predetermined by the modern ranges of almost all genera of seagrasses, stretches from the southwestern waters of eastern Gondwana to the northwestern waters of the Eurasian part of Laurasia. The main route of movement of diasporas and seagrasses populations was the Tethys water area, which was modified in the Late Mesozoic and early Cenozoic. It was revealed that the main method of dispersal of seagrasses was long-distance dispersal, which is confirmed by both molecular genetic data and very fast (on a geological time scale) processes of penetration into new water areas, and analysis of the features of dissemination of modern representatives. An alternative vicar scenario was proposed only for the reconstruction of the formation of the Posidonia range.

OxDNA to Study Species Interactions.

Molecular ecology uses molecular genetic data to answer traditional ecological questions in biogeography and biodiversity, among others. Several ecological principles, such as the niche hypothesis and the competitive exclusions, are based on the fact that species compete for resources. More in generally, it is now recognized that species interactions play a crucial role in determining the coexistence and abundance of species. However, experimentally controllable platforms, which allow us to study and measure competitions among species, are rare and difficult to implement. In this work, we suggest exploiting a Molecular Dynamics coarse-grained model to study interactions among single strands of DNA, representing individuals of different species, which compete for binding to other oligomers considered as resources. In particular, the well-established knowledge of DNA–DNA interactions at the nanoscale allows us to test the hypothesis that the maximum consecutive overlap between pairs of oligomers measure the species’ competitive advantages. However, we suggest that a more complex structure also plays a role in the ability of the species to successfully bind to the target resource oligomer. We complement the simulations with experiments on populations of DNA strands which qualitatively confirm our hypotheses. These tools constitute a promising starting point for further developments concerning the study of controlled, DNA-based, artificial ecosystems.

Correlation of anatomical involvement patterns of insular gliomas with subnetworks of the limbic system.

Gliomas frequently involve the insula both primarily and secondarily by invasion. Despite the high connectivity of the human insula, gliomas do not spread randomly to or from the insula but follow stereotypical anatomical involvement patterns. In the majority of cases, these patterns correspond to the intrinsic connectivity of the limbic system, except for tumors with aggressive biology. On the basis of these observations, the authors hypothesized that these different involvement patterns may be correlated with distinct outcomes and analyzed these correlations in an institutional cohort. Fifty-nine patients who had undergone surgery for insular diffuse gliomas and had complete demographic, pre- and postoperative imaging, pathology, molecular genetics, and clinical follow-up data were included in the analysis (median age 37 years, range 21-71 years, M/F ratio 1.68). Patients with gliomatosis and those with only minor involvement of the insula were excluded. The presence of T2-hyperintense tumor infiltration was evaluated in 12 anatomical structures. Hierarchical biclustering was used to identify co-involved structures, and the findings were correlated with established functional anatomy knowledge. Overall survival was evaluated using Kaplan-Meier and Cox proportional hazards regression analysis (17 parameters). The tumors involved the anterior insula (98.3%), posterior insula (67.8%), temporal operculum (47.5%), amygdala (42.4%), frontal operculum (40.7%), temporal pole (39%), parolfactory area (35.6%), hypothalamus (23.7%), hippocampus (16.9%), thalamus (6.8%), striatum (5.1%), and cingulate gyrus (3.4%). A mean 4.2 ± 2.6 structures were involved. On the basis of hierarchical biclustering, 7 involvement patterns were identified and correlated with cortical functional anatomy (pure insular [11.9%], olfactocentric [15.3%], olfactoopercular [33.9%], operculoinsular [15.3%], striatoinsular [3.4%], translimbic [11.9%], and multifocal [8.5%] patterns). Cox regression identified hippocampal involvement (p = 0.006) and postoperative tumor volume (p = 0.027) as significant negative independent prognosticators of overall survival and extent of resection (p = 0.015) as a significant positive independent prognosticator. The study findings indicate that insular gliomas primarily involve the olfactocentric limbic girdle and that involvement in the hippocampocentric limbic girdle is associated with a worse prognosis.

Molecular Genetic Investigation of Digital Melanoma in Dogs.

Canine digital melanoma, in contrast to canine oral melanoma, is still largely unexplored at the molecular genetic level. The aim of this study was to detect mutant genes in digital melanoma. Paraffin-embedded samples from 86 canine digital melanomas were examined for the BRAF V595E variant by digital droplet PCR (ddPCR), and for exon 11 mutations in c-kit. Furthermore, exons 2 and 3 of KRAS and NRAS were analysed by Sanger sequencing. Copy number variations (CNV) of KITLG in genomic DNA were analysed from nine dogs. The BRAF V595E variant was absent and in c-kit, a single nucleotide polymorphism was found in 16/70 tumours (23%). The number of copies of KITLG varied between 4 and 6. KRAS exon 2 codons 12 and 13 were mutated in 22/86 (25.6%) of the melanomas examined. Other mutually exclusive RAS mutations were found within the hotspot loci, i.e., KRAS exon 3 codon 61: 2/55 (3.6%); NRAS exon 2 codons 12 and 13: 2/83 (2.4%); and NRAS exon 3 codon 61: 9/86 (10.5%). However, no correlation could be established between histological malignancy criteria, survival times and the presence of RAS mutations. In summary, canine digital melanoma differs from molecular genetic data of canine oral melanoma and human melanoma, especially regarding the proportion of RAS mutations.

First evidence of White-footed Deer Mouse (&lt;i&gt;Peromyscus leucopus&lt;/i&gt;) on mainland New Brunswick, Canada

White-footed Deer Mouse (Peromyscus leucopus) and the closely related, and more northerly ranging, Deer Mouse (Peromyscus maniculatus) broadly overlap in distribution and are often difficult to distinguish from each other. Based on molecular genetic data (cytochrome b gene), we report two new distribution records for P. leucopus for New Brunswick, Canada, the first mainland localities for this species in the province. Previous sampling of Peromyscus in New Brunswick may have overlooked the presence of P. leucopus, possibly because the specimens collected were all assumed to be P. maniculatus. However, current detection in New Brunswick may be part of a broader recent northward range expansion documented to be underway in P. leucopus. Although our use of a single mitochondrial gene to identify P. leucopus does not eliminate the possibility that the New Brunswick specimens are of hybrid origin, our results support the presence of P. leucopus in New Brunswick and suggest more detailed analyses will be required to determine the nature of any genetic interaction between P. leucopus and P. maniculatus in the province. Recognition of morphologically cryptic Peromyscus in southern New Brunswick also emphasizes the need to incorporate comprehensive methods to ensure the correct identification of specimens of this genus in Maritime Canada. We also note the potential implications of this discovery with respect to the incidence of Lyme disease in New Brunswick.

REVEALING THE MOLECULAR-GENETIC AND CLINICAL PREDICTORS OF GLUCOCORTICOID RESISTANCE IN PATIENTS WITH HAND ECZEMA.

The aim: To reveal the possible predictors of the glucocorticoid resistance in patients with hand eczema (HE) based on the demographic, clinical, and molecular-genetic data. Materials and methods: 143 patients with HE were included in the study. Demographic, clinical, biochemical (blood content of IgE, IL-17A, IL-2, 25(OH)D), and genetic (rs41423247 genotypes) data were obtained from all patients. Results: After 2 weeks of treatment by glucocorticoids, all subjects were divided into "responder" and "non-responder" groups according to change of the Hand Eczema Severity Index (HECSI). Statistical analysis was done using SPSS (version 22.0.). Binary logistic regression was used to identify predictors of glucocorticoid resistance. P-value 0.05). The results of the multivariate regression showed that Bcl-1 G-allele (OR =3.83; P = 0.033), and severe eczema (OR = 2.52; P = 0.023) are linked with an elevated risk of glucocorticoid resistance in patients with hand eczema. Conclusions: Insensitivity to glucocorticoids in HE patients is associated with NR3C1 gene Bcl-1 polymorphism, eczema severity and blood level of IL-17, IL-2, 25(OH)D. The final adjustment showed that minor C-allele of the Bcl-1 polymorphism and severe eczema are the strongest predictors of the glucocorticoid resistance.

Origin and genetic nature of polyploidy in paleoendemic coast redwood (Sequoia sempervirens (D. Don) Endl.)

Abstract It is not known when the polyploid coast redwood (Sequoia sempervirens) evolved from its diploid ancestors, and what is its type of polyploidy. Whether close relatives of Sequoia, giant sequoia (Sequoiadendron giganteum) and dawn redwood (Metasequoia glyptostroboides), have possibly contributed to the ancestry of hexaploid of Sequoia remains an open question. The nature of hexaploidy in Sequoia has baffled biologists for more than a century. Based on the chromosome configurations in Sequoia, G. Ledyard Stebbins was the first geneticists who postulated in 1948 that Sequoia is an autoallohexaploid (AAAABB), and an ancient species of Metasequoia might have been one of the putative ancestors of Sequoia. After its chromosome number (2n=6x=66) was confirmed in hexaploid Sequoia, the type of polyploidy in Sequoia has been further investigated for the past 70 years by a number of investigators, using cytogenetic and genetic data. Although an autoallohexaploid (AAAABB) origin of Sequoia has remained one of the dominant hypotheses until recently, an alternative hypothesis, amongst other possible origins, was also put forth by Ahuja and Neale (2002), that Sequoia may be partially diploidized autohexaploid (AAAAAA), derived from some ancestral species of Sequoia, thus carrying a single ancestral genome. Cytogenetic, molecular genetics, and genome sequence data now support the hypothesis that Sequoia originated as an autohexaploid.

High diversity of small insectivorous mammals on Qinghai\u2013Tibet Plateau and first description of karyotype for four endemics of China

Among seven species of the order Eulipotyphla (from southern Gansu and northern Sichuan Provinces, Central China) studied cytogenetically, karyotypes of one talpid species, Uropsilus aff. soricipes (2n = 36, NFa = 54), and three soricid species, Chodsigoa hypsibia (2n = 65, NFa = 66), Sorex cansulus (2n = 42, NFa = 64) and Sorex thibetanus (2n = 42, NFa = 60), are described cytogenetically for the first time. All four species are endemic to China with distribution ranges restricted to the Qinghai–Tibet Plateau and adjacent mountain ranges. The Ch. hypsibia karyotype consists of mostly acrocentric autosomes and one metacentric pair of autosomes; besides, a B chromosome was identified. No polymorphism was detected among karyotypes of other species, including shrews Sorex bedfordiae (2n = 26, NFa = 44), Anourosorex squamipes (2n = 48, NFa = 92) and Crocidura suaveolens (2n = 40, NFa = 44). The Chinese shrew mole U. aff. soricipes and three shrew species (S. bedfordiae, Ch. hypsibia and A. squamipes) represent autochthonous fauna of Central/Western China, whereas S. thibetanus, S. cansulus and C. suaveolens belong to phylogenetic groups occurring mostly to the north and west from China; therefore, they should be considered relatively recent colonisers. Thus, considering the relationships of the species within phylogenetic groups, our results on karyotypes are in good agreement with molecular genetic data.