Cassava is a major tropical food crop in the Euphorbiaceae family that has high carbohydrate production potential and adaptability to diverse environments. Here we present the draft genome sequences of a wild ancestor and a domesticated variety of cassava and comparative analyses with a partial inbred line. We identify 1,584 and 1,678 gene models specific to the wild and domesticated varieties, respectively, and discover high heterozygosity and millions of single-nucleotide variations. Our analyses reveal that genes involved in photosynthesis, starch accumulation and abiotic stresses have been positively selected, whereas those involved in cell wall biosynthesis and secondary metabolism, including cyanogenic glucoside formation, have been negatively selected in the cultivated varieties, reflecting the result of natural selection and domestication. Differences in microRNA genes and retrotransposon regulation could partly explain an increased carbon flux towards starch accumulation and reduced cyanogenic glucoside accumulation in domesticated cassava. These results may contribute to genetic improvement of cassava through better understanding of its biology.
Inflammatory pseudotumor (IPT)-like follicular dendritic cell (FDC) sarcoma is a recently described rare tumor and considered a unique entity, with different histologic appearances and behavior from those of the classical FDC sarcoma. This study analyzed the clinical and pathological findings of two such cases that the authors encountered and 36 previously reported cases identified in the literature. Assessment of all 38 cases showed a slight female predominance (2.2:1) with a median age of 56.5 years. Seventeen patients complained of abdominal discomfort or pain, while fifteen patients had no clinical symptom. Almost all cases occurred in liver (n=20) or spleen (n=17). Except in one case, all patients underwent surgical resection of the tumor alone. Histologic features showed a mixture of chronic inflammatory cells and variable amounts of spindle cells with vesicular nuclei and distinct nucleoli. The tumor cells expressed conventional FDC markers such as CD21 (75%), CD35 (92%), CD23 (62%), clusterin (75%), and CNA.42 (100%). EBV was detected in thirty-five cases (92.1%) by Epstein-Barr virus (EBV)-encoded RNA in situ hybridization, and EBV-latent membrane protein-1 was expressed in 90% of the cases. With a median follow-up of 21 months, 29 patients (85.3%) were alive and well, 4 (11.8%) were alive with disease, one patient (2.9%) died of disease. Only four patients with hepatic tumors underwent recurrence or metastasis after initial treatment. Epstein-Barr virus is thought to play a role in the development of the tumor; however, the pathogenesis of the disease and the origin of tumor cells remain unclear.
Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a common and economically important crop in Asia. Specific targets of plant breeding programs for cabbage have been improvement in yield, resistance to environment stresses, and nutrition quality by means of genetic manipulation. To obtain information on yield improvement applicable for the genetic engineering approach, we have attempted to dissect the molecular pathways that regulate organ size. We first isolated a putative homolog of ARGOS full-length cDNA from Chinese cabbage leaves, which we designated BrARGOS. At the transcription level, BrARGOS was detected in all organs tested in Chinese cabbage. To test the function of this gene, we then engineered Arabidopsis plants that would overexpress BrARGOS ectopically. The organs of the transgenic Arabidopsis plants were significantly larger than those of the control plants. This increase in size was due to enhanced cell proliferation, with no contribution from cell expansion. The molecular analysis revealed that overexpression of BrARGOS up-regulated the transcription of several genes involved in the control of organ size. These results suggest that the BrARGOS gene may function as one of the regulators of organ size in Chinese cabbage. As such, manipulation of the BrARGOS gene may significantly increase the size of Chinese cabbage organs, such as Chinese cabbage heads.
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