Production of Spontaneous Diploid Lines from Isolated Microspores Following Cryopreservation in Spring Rapeseed (Brassica napus L.)

Cryopreservation of microspores provides a potentially powerful means for increasing percentage of spontaneous diploids in microspore-derived populations in rapeseed (Brassica napus L.). This study was to investigate the production of spontaneous diploid lines in relation to steps of cryopreserving micro-spores of two spring rapeseed breeding lines G-231 and M3-124. Microspores of both genotypes were isolated and subjected to Cryopreservation. The step of cooling process (before liquid nitrogen immersion) in a Cryopreservation protocol resulted in high percentages of spontaneous diploids in lines regenerated from frozen microspores in both genotypes. Liquid nitrogen immersion and subsequent thawing process had no influence on the percentage of spontaneous diploids. A linear relationship between percentage of spontaneous diploids and cooling temperatures was detected. The lowest cooling temperature of ?40 °C yielded the highest percentages of spontaneous diploids (51.1 % in G-231 and 47.7 % in M3-124, respectively), which were more than doubled in comparison to those in the corresponding unfrozen controls. The current study indicated that cold treatment may be utilized to greatly enhance the percentage of spontaneous diploids in rapeseed breeding programs.     

Cytological study on haploid male fertility in maize

Doubled haploid (DH) breeding technology, which relies on haploid genome doubling, is widely used in commercial maize breeding. Spontaneous haploid genome doubling (SHGD), a more simplified and straightforward method, is gaining popularity among maize breeders. However, the cytological mechanism of SHGD remains unclear. This study crossed inbred lines RL36 and RL7, which have differing SHGD abilities, with inducer line YHI-1 to obtain haploid kernels. The meiotic processes of pollen mother cells (PMCs) in the haploid plants were compared with diploid controls. The results suggested that three main pathways, the early doubling of haploid PMCs, the first meiotic metaphase chromosomal segregation distortion, and anomaly of the second meiosis, are responsible for SHGD. Furthermore, flow cytometry analysis of ploidy levels in leaves and PMCs from haploids and diploid controls revealed that somatic cell chromosome doubling and germ cell chromosome doubling are independent processes. These findings provide a foundation for further studies on the underlying mechanism of SHGD, aiding the application of DH technology in maize breeding practices.     

含硫油品储罐自燃机理及预防技术研究

介绍了含硫油品储罐自燃机理的研究现状及进展,研究了活性硫对不同类型储罐的腐蚀机理以及硫化亚铁的形成过程.指出事故的原因是由罐的腐蚀产物硫化亚铁氧化放热所引起,提出采用消除石油炼制过程中的硫和将产生的硫化亚铁清洗或转变为其他形式方法,可以预防硫化亚铁的自燃.     

煤矸石渣土改良及其效果研究

自燃煤矸石山渣土具有高盐强酸性,严重制约了植物的生长,因此在对自燃煤矸石山进行植被恢复时,首先要对煤矸石山渣土进行改良。以研究区内黄土作为改良剂,研究了其对自燃煤矸石渣土的改良方法和效果。选取高羊茅、刺槐、紫穗槐、侧柏、山皂角在改良后的渣土中进行种植实验,测试改良效果,筛选适宜在煤矸石山上种植的植物,并确定黄土作为改良剂的施用比例。改良实验结果表明,黄土作为改良剂对自燃煤矸石渣土的强酸性改良效果良好,在pH值为2.8的强酸性渣土中,加入25%的黄土,pH值可提高到6.8。对自燃煤矸石渣土的高盐性改良效果较差,在盐分为3.8%的煤矸石渣土中,加入62.5%的黄土,盐分可降低至0.97%。种植实验也表明,高羊茅、紫穗槐、山皂角对改良后煤矸石渣土的适应性较强,刺槐、侧柏的适应性则较弱。     

A Case Report of a Malignant Fibrous Histiocytoma in a T-cell Receptor β Chain and p53 Double-knockout Mouse

A subcutaneous tumor was found in the right abdomen of a 16-week-old male TCRβ and p53 double-knockout mouse. The tumor had indistinct borders with the surrounding tissue. The cut surface after formalin fixation was pale yellowish white, partially dark red and partly white. Histologically, the tumor was composed of three distinct regions. The first region showed pleomorphic cells arranged in sheets. The second region showed spindle cells arranged in interlacing fascicles. The final region contained a mixture of the above mentioned two types of cells. Furthermore, a small amount of collagen fibers, round cells, multinucleated giant cells, and cells with eosinophilic granules were observed between these tumor cells. Immunohistochemical examination and electron microscopy identified that the pleomorphic cells and spindle cells were histiocytes and fibroblasts, respectively, and that the round cells were undifferentiated mesenchymal cells. Based on these findings, the tumor was diagnosed as a malignant fibrous histiocytoma.     

Uterine Carcinosarcoma in a 2-year-old Female Wistar Hannover GALAS Rat

Carcinosarcomas are rare tumors in humans as well as rats and most commonly occur in the uterus. Recently, we observed a case of incidental carcinosarcoma of the uterus in a female Wistar Hannover GALAS [BrlHan:WIST@ Jcl (GALAS)] rat at 2 years of age. Histopathologically, the tumor was characterized by an admixture of malignant epithelial and nonepithelial elements. The carcinomatous components represented a type of endometrial carcinoma, consisting of glandular and solid proliferation of large-sized tumor cells. Prominent mitoses and tumor cell invasion were observed. The sarcomatous components were characterized by multifocal proliferation of severe atypical cells with cartilage matrix and were diagnosed as chondrosarcoma. Transitions between carcinomatous and sarcomatous components were observed, and many tumor cells in the solid lesion showed immunohistochemical reactivity with both cytokeratin and vimentin. Based on these findings, this tumor was diagnosed as a uterine carcinosarcoma. This is the first report of uterine carcinosarcoma in Wistar Hannover GALAS [BrlHan:WIST@Jcl (GALAS)] rats.     

Increasing the genetic uniformity of bighead carp [Aristichthys nobilis (Richardson)] by means of spontaneous diploidization of gynogenetically activated eggs

Three groups of gynogenetic diploid bighead carp were successfully obtained by means of artificial gynogenesis. The activation rates of gynogenesis varied from 75.9% to 98.8%, and the frequency of spontaneous diploidization was around 0.4%. Over 2000 normally gynogenetic diploid fry were obtained in three gynogenetic groups. The haploid karyotype consisted of nine metacentric, 12 submetacentric, three subtelocentric chromosomes and 45 arms. The chromosome number was 48 from gynogenetic diploid. The results showed that the genetic material of offspring was maternal. The aneuploid hybrid embryos of bighead carp and Xingguo red common carp with chromosome numbers ranging from 28 to 73 did not survive post hatch, likely the result of incompatibility between the nucleus and the cytoplasm of two parents. Sixty RAPD primers from three groups were used for total DNA amplification of gynogenetic offspring, maternal and ‘paternal’ fish. A total of 451 bands were amplified from three kinds of samples above. From maternal bighead carp, 256 bands were amplified; however, there were 251 shared bands between maternal and gynogenetic bighead carp. From artificial gynogenetic offspring, two ‘paternal’ DNA segments without an expression function were found. An UPGMA tree showed that gynogenetic offspring were closely clustered and the genetic identity among them was very high (0.956).     

HYPERTHERMIA AND RADIATION THERAPY IN CANCER TREATMENT*

Hyperthermia is a field of cancer research of increasing importance to veterinarians and physicians. The thermobiologic studies that are guiding the development of clinical research are reviewed. The interaction of heat, radiation, and drugs on tumors and normal tissues is presented, and the basis for producing a therapeutic gain is discussed. Current methods of inducing local, regional, and systemic hyperthermia in animals and humans are summarized. The areas of clinical research in which veterinary radiologists and oncologists could contribute by studying the effects of heat and radiotherapy on domestic animals with spontaneous tumors are emphasized.     

SPONTANEOUS REGRESSION OF PULMONARY METASTASES IN A DOG*

Spontaneous regression of presumed lung metastases was diagnosed in an Irish Wolfhound which had a previous pelvic limb amputation for tibial fibrosarcoma. Literature on spontaneous regression in man is reviewed and implications of spontaneous tumor regression for animal patients are discussed.