Escape efficiency of diploid and polyploid frogs: A comparison ofOdontophrynus cultripes (2n=22) andO. americanus (4n=44)

The escape efficiency of two closely related species of frogs,Odontophrynus cultripes(2n=22) and the tetraploidO. americanus (4n=44), were compared in a shuttle box and under simulated naturalistic conditions.O. americanus was generally superior toO. cultripes, and females tended to outperform males within both species. The relative inefficiency ofO. cultripes escape behavior was examined in light of the animals' having an elaborate, passive defense mechanism in the form of well-marked venom glands. Escape efficiency was highly variable in both species. Possessing twice the amount of DNA, the tetraploid behavioral variation was paradoxically less than that of the diploid, but compatible with what has been found for morphological characters in other organisms.This research was carried out at the Instituto Butantan with the support of ongoing grants from the Brazilian CNPq, FAPESP, FEDIB, and PNUD while the first author was a visiting professor in the Departamento de Genética Humana, Instituto de Biociências, Universidade de São Paulo, under the auspices of the Programa Multinacional de Genética, Organization of American States.     

An efficient multiple-exposure analysis of the toxicity of crisnatol,a DNA intercalator in phase II clinical trials

To investigate the toxicity and mechanism of action of crisnatol (CRS), a new DNA intercalator currently in phase II clinical trials, we analyzed cellular and nuclear flow cytometric (FCM) parameters of murine erythroleukemic cells (MELC) exposed to a range of CRS concentrations over three exposure conditions: short-term (4 h), long-term (24 h), and short-term with recovery (4 h⁺/19 h^–). At 0.5–1.0M CRS, 4 h exposure results in a reversible G₂-phase block, while 24 h exposure results in > G₂ polyploidy. At 5–10M CRS concentrations, cells exhibit persistent retardation of S-phase progression or irreversible G₂ and/or > G₂ blocks, depending on duration of exposure. Cells terminally blocked in G₂ exhibit increased nuclear/cellular volumes and increased nuclear fluorescein isothiocyanate (protein) staining, suggestive of unbalanced growth. At 25–50M CRS concentrations, MELC exhibit severe membrane perturbation (loss of viability) regardless of exposure. In contrast, following similar exposures to an inactive isomer of CRS, MELC exhibit minimal cell cycle effects, suggesting that cell cycle kinetics may be a useful criterion for assessing potential efficacy. Similar analyses with different classes of chemotherapeutic agents reveal that the range of induced cellular/nuclear perturbations varies with the class of compound used. Taken together, these results suggest that drug toxicity can vary with both concentration and duration of exposure and, as such, a selective multiple-exposure FCM analysis may better represent the spectrum of drug action for drug development and pharmacodynamic studies.Abbreviations m-AMSA amsacrine - ARA-C cytosine arabinoside - BrdU 5-bromodeoxyuridine - CF 5,6-carboxyfluorescein - CFDA 5,6-carboxyfluorescein diacetate - CRS crisnatol - FCM flow cytometry - FITC fluorescein isothiocyanate - 5-FU 5-fluorouracil - DMSO dimethylsulfoxide - MELC Friend murine erythroleukemic cell - MLP melphalan - PBS phosphate-buffered saline - PI propidium iodide - TAX taxol - topo topoisomerase - VBL vinblastine sulfate - cis-Pt cis-platinum     

Maternal siRNAs as regulators of parental genome imbalance and gene expression in endosperm of Arabidopsis seeds

Seed size is important to crop domestication and natural selection and is affected by the balance of maternal and paternal genomes in endosperm. Endosperm, like placenta in mammals, provides reserves to the developing embryo. Interploidy crosses disrupt the genome balance in endosperm and alter seed size. Specifically, paternal-excess crosses (2 × 4) delay endosperm cellularization (EC) and produce larger seeds, whereas maternal-excess crosses (4 × 2) promote precocious EC and produce smaller seeds. The mechanisms for responding to the parental genome dosage imbalance and for gene expression changes in endosperm are unknown. In plants, RNA polymerase IV (PolIV or p4) encoded by NRPD1a is required for biogenesis of a major class of 24-nt small interfering RNAs (also known as p4-siRNAs), which are predominately expressed in developing endosperm. Here we show that p4-siRNA accumulation depends on the maternal genome dosage, and maternal p4-siRNAs target transposable elements (TEs) and TE-associated genes (TAGs) in seeds. The p4-siRNAs correlate negatively with expression levels of AGAMOUS-LIKE (AGL) genes in endosperm of interploidy crosses. Moreover, disruption of maternal NRPD1a expression is associated with p4-siRNA reduction and AGL up-regulation in endosperm of reciprocal crosses. This is unique genetic evidence for maternal siRNAs in response to parental genome imbalance and in control of transposons and gene expression during endosperm development.     

Determining the need for rescue intracytoplasmic sperm injection in partial fertilisation failure during a conventional IVF cycle

To explore the need for rescue intracytoplasmic sperm injection (ICSI) in cases of partial fertilisation failure during a conventional in vitro fertilisation cycle, rescue ICSI was performed for cycles with a fertilisation rate of <50%. The data were divided into three groups based on the fertilisation rate: group 1 (0%), group 2 (<25%) and group 3 (>25%). The impact of rescue ICSI on each group was then analysed in terms of ovum fertilisation, embryo development, embryo utilisation and selection of embryos for transfer. Rescue ICSI was performed on 1831 unfertilised oocytes from 313 cycles. The fertilisation rates for group 1, group 2 and group 3 were 74.66, 68.35 and 65.46%, and the rate of polyploidy in the three groups was 8.55, 11.33, and 14.47%. The percentage of embryos that can be transferred from rescue ICSI for group 2 was 38.33%, and this value was higher than those of the other two groups. It is concluded that rescue ICSI is not recommended for patients with an IVF rate of >25% as the procedure is associated with a greater risk and low returns. However, it is feasible to perform rescue ICSI for patients with IVF rates of <25%.     

The ultrastructure of polyploid B-cells in the islets of normal mice

Summary Light and electron microscopic studies of diploid, tetraploid and octaploid B-cells in the islets of normal C57BL/KsJ mice revealed that polyploid cells were characterized by a wider range of granulated states than diploid B-cells. The maximum granule densities were similar for polyploid and diploid cells; however, some polyploid cells were almost devoid of granules, while the least granulated diploid cells contained intermediate granule densities. The tetraploid cells also appeared to be characterized by an increased mitochondrial stage which suggests compensation for the greater degree of degranulation. These observations were confirmed by morphometric analysis. Two interpretations of the apparent polyploidy are discussed; that polyploid B-cells may be more responsive to insulin releasing stimuli than diploid B-cells and that tetraploid cells may only be diploid cells in the G₂ phase of the mitotic cycle.     

Childhood near‐tetraploid acute lymphoblastic leukemia: an EGIL study on 36 cases

Objectives: Patients with near‐tetraploid (karyotype: 81 – 103 chromosomes) acute lymphoblastic leukemia (NT‐ALL) constitute about 1% of childhood ALL and data reported on them are limited and controversial. The aim of the study was to enlarge the knowledge on these rarely occurring ALL. Methods: The members of the European Group for Immunophenotyping of Leukemias (EGIL) searched retrospectively their databases for NT‐ALL patients. Results: We collected data of 36 European children from seven European countries with NT‐ALL diagnosed since 1992. All patients reached complete remission (CR) after induction chemotherapy. Their blasts were negative for peroxidase and BCR‐ABL1. Ten children were diagnosed as T‐cell ALL (T‐ALL) EGIL categories (T‐I n = 2, T‐II n = 2, T‐III n = 3, T‐IV n = 3) and four displayed various structural chromosomal abnormalities. Eight of 10 T‐ALL remained in 1st CR; one died in CR from sepsis and one is alive in 2nd CR. Median survival was 88 (7–213) months. B‐cell precursor (BCP) ALL was diagnosed in 26 children. Thirteen were positive for ETV6‐RUNX1 and are alive in 1st CR for 32–147 months. Ten children were ETV6‐RUNX1 negative and remained in 1st CR for 16–163 months. One girl with hypodiploid and NT metaphases and ETV6‐RUNX1‐negative BCP‐ALL and one of two boys with NT‐BCP‐ALL not examined for ETV6‐RUNX1 died of infection after stem cell transplantation in 2nd/3rd CR. Secondary myelodysplastic syndrome developed in two patients with NT‐BCP‐ALL. Conclusions: Our data demonstrate immunophenotypic, cytogenetic, and molecular heterogeneity of NT‐ALL and favorable prognosis of most NT‐ALL across different immunophenotypic and/or genetic ALL subtypes.     

Clinical features of diffuse large B‐cell lymphoma with polyploidy

Polyploidy, defined as more than two sets of homologous chromosomes, is found in a variety of malignant tumors and is thought to be related to disease pathogenesis. However, there have been no studies that have investigated polyploidy in diffuse large B‐cell lymphoma (DLBCL). Here we reviewed clinicopathological features of 16 cases of DLBCL with polypoidy, which was defined as DLBCL with either near‐tetraploid or greater number of chromosomes as detected by the G‐band method. The frequency of polyploid DLBCL was 2.9 % (16/544), including 15 near‐tetraploid and one near‐pentaploid case. CD5, CD30 and EBER positive cases were 13 % (2/16), 13 % (2/16) and 6 % (1/16), respectively. Bcl2 positive cases were 75 % (12/16). The numbers of huge and multinucleated cells were higher in polyploid than in non‐polyploid DLBCL (P = 0.0029 and P < 0.0001, respectively). Clinical features of polyploid DLBCL included reduced infiltration of extranodal sites (2/15, 13 %) and major lymph node infiltration. Of seven cases that received chemotherapy, six responded to treatment and survived. Our results suggest that polyploid DLBCL represents a clinicopathologically characteristic group of DLBCL. This knowledge can be useful for informing more personalized and targeted management of DLBCL patients.     

Partitioned expression of duplicated genes during development and evolution of a single cell in a polyploid plant

Polyploidy is an important driver of eukaryotic evolution, evident in many animals, fungi, and plants. One consequence of polyploidy is subfunctionalization, in which the ancestral expression profile becomes partitioned among duplicated genes (termed homoeologs). Subfunctionalization appears to be a common phenomenon insofar as it has been studied, at the scale of organs. Here, we use a high-resolution methodology to investigate the expression of thousands of pairs of homoeologs during the development of a single plant cell, using as a model the seed trichomes ("cotton fiber") of allopolyploid (containing "A" and "D" genomes) cotton (Gossypium). We demonstrate that approximately 30% of the homoeologs are significantly A- or D-biased at each of three time points studied during fiber development. Genes differentially biased toward the A or D genome belong to different biological processes, illustrating the functional partitioning of genomic contributions during cellular development. Interestingly, expression of the biased genes was shifted strongly toward the agronomically inferior D genome. Analyses of homoeologous gene expression during development of this cell showed that one-fifth of the genes exhibit changes in A/D ratios, indicating that significant alteration in duplicated gene expression is fairly frequent even at the level of development and maturation of a single cell. Comparing changes in homoeolog expression in cultivated versus wild cotton showed that most homoeolog expression bias reflects polyploidy rather than domestication. Evidence suggests, however, that domestication may increase expression bias in fibers toward the D genome, potentially implicating D-genome recruitment under human selection during domestication.     

秋水仙素诱导茴香多倍体的研究

目的探讨不同秋水仙素浓度和不同处理时间诱导茴香多倍体的效果。方法采用种子浸泡法以不同秋水仙素浓度、不同处理时间诱导下的种子的萌发率和诱变率、胚根诱变体的外部形态、染色体数量、内部组织构造以及精油量和成分进行了比较。结果诱导液质量浓度为0.13%,处理时间为24 h时的诱导效果最好;诱导后的突变体胚根与对照相比,表现粗大、染色体数目明显增加、胚根的内部细胞数量明显增多、4种主要精油成分中除莳萝芹菜脑略低于对照外,柠檬酸、反式-茴香脑和莰烯3种成分均显著提高。结论秋水仙素诱导的突变体可以较大幅度地提高茴香主要精油成分的量,为茴香高精油量多倍体新品种的培育提供了依据。