First Report of Pestalotiopsis mangiferae and P. vismiae Causing Twig Dieback of Myrica rubra in China.

Chinese bayberry (Myrica rubra Siebold & Zucc.), an evergreen fruit tree, is widely grown in southern China. In 1999, severe twig dieback was observed on M. rubra in Taizhou and it spread to several major M. Rubra-producing areas of Zhejiang covering more than 6,000 ha by 2011. Symptoms were usually observed from June to November and first appeared as chlorosis of leaves and leaf drop, followed by the formation of dark brown lesions covered with white mycelia surrounding leaf scars. The lesions can extend to the whole twig and tree causing discoloration of the xylem. In most cases, infected trees die within 1 to 4 years. Two distinct fungi totaling 46 isolates were isolated from the surface-disinfested diseased twigs and cultured on potato dextrose agar (PDA) at 28°C. An isolate of each fungus, designated as C1 and B1, was characterized further following 10 days of growth on PDA at 28°C. C1 formed zonate, white colonies and black, acervular conidiomata with the conidia aggregated on acervuli as a creamy mass. Isolate B1 formed nonzonate, white colonies and black, acervular conidiomata with the conidia aggregated on acervuli as droplets. Conidia for each isolate were fusiform with five cells; one hyaline apical cell, one hyaline basal cell, and three, dark brown median cells. Conidia ranged from 17.8 to 25.2 × 6.7 to 9.2 µm for C1 and 21.2 to 27.8 × 4.3 to 7.5 µm for B1. There were two to three hyaline, filamentous appendages (9.8 to 23.5 µm long for C1 and 10.5 to 25.5 µm long for B1) attached to each apical cell, and one hyaline appendage (3.5 to 7.2 µm long for C1 and 3.0 to 6.8 µm long for B1) attached to each basal cell. The cultural and morphological characteristics of C1 (16 isolates) matched the description for Pestalotiopsis mangiferae while B1 (27 isolates) matched the description for P. vismiae (2). The PCR-amplified and sequenced internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1-5.8S-ITS2) for isolate C1 (GenBank Accession No. JQ281542) and B1 (GenBank Accession No. JQ281543) were 99 and 100% homologous to that of the P. mangiferae isolate MM 102 (GenBank Accession No. GU722595) and P. vismiae isolate xsd08116 (GenBank Accession No. FJ481027), respectively. For pathogenicity tests, nine healthy detached leaves and 12 potted plants of M. rubra were wound inoculated with sterile water (control) or conidial suspensions (105 conidia per ml; 20 µl on each site) of C1 and B1, respectively, and maintained with relative humidity of more than 90% under fluorescent light at 28°C. Tests were performed twice. Necrotic lesions, resembling those that occurred in the field, were observed on all inoculated detached leaves and 33.3% of C1 and 25% of B1 inoculated potted plants 10 and 30 days following inoculation, respectively, while the controls remained healthy. Two fungi were reisolated from the lesions with identical morphology to the initial C1 and B1 inoculums. Therefore, P. mangiferae and P. vismiae were determined to be the causal agent for twig dieback of M. rubra in China. Pestalotiopsis spp. were previously reported as pathogens of loquat (4), mango (3), and blueberry (1) causing economic loss. To our knowledge, this is the first report of twig dieback disease of M. rubra caused by P. mangiferae and P. vismiae. References: (1) J. G. Espinoza et al. Plant Dis. 92:1407, 2008. (2) Q. X. Ge et al. Flora Fungorum Sinicorum. Vol. 38, Pestalotiopsis. Science Press, Beijing, 2009. (3). Y. Ko et al. Plant Dis. 91:1684, 2007. (4). A. E. Perelló and S. Larran. Plant Dis. 83:695, 1999.

Analysis of antigen epitopes and molecular pathogenic characteristics of the 2009 H1N1 pandemic influenza A virus in China.

In order to further predict the epidemic trend and develop vaccines for 2009 H1N1 virus, we monitored its epitopes and molecular pathogenic characteristics during the epidemic process. We also analyzed the similarity of antigenic and genetic characteristics among the novel 2009 H1N1, representative seasonal H1N1 strains, and vaccine strains. 2009 H1N1 isolates had high similarity of hemagglutinin (HA) antigenic sites with H1N1 viruses isolated before 1940 and up to 80.0% similarity with 1918 H1N1. The elderly people born before 1940 have relatively low 2009 H1N1 infection rate, which might be responsible for their previous infection with either 1918 H1N1 virus or an early progeny. Compared to seasonal H1N1 vaccine strains from 1999 to 2010, the HA, neuraminidase (NA), and nucleoprotein (NP) proteins of the isolates had highly conserved CTL epitopes (60.5-65.8%, 69.6-82.6%, and 76.7%, respectively). The seriousness and mortality rate of 2009 H1N1 infections were similar to seasonal influenza, which may be related to the molecular characteristics of low toxicity of 2009 H1N1 and cross-T-cell immunity, due to vaccination or exposure to seasonal H1N1 virus. Some strains of 2009 H1N1 acquired mutations at antigenic and glycosylation sites. It is of particular interest that Haishu/SWL110/10 and Beijing/SE2649/09, isolated after November 2009, gained a new glycosylation site at the position 179 of HA protein, near the RBD. Thus, in the future, vaccination with glycosylated 2009 H1N1 virus may prevent the seasonal epidemic caused by strains with glycosylation site mutation near the receptor binding domain (RBD).

DNA flow cytometry from paraffin-embedded tissue in diagnosis of cutaneous malignant lymphomas and pseudolymphomas.

DNA content and cell cycle distributions in paraffin-embedded blocks of 111 skin biopsy specimens of 70 patients with cutaneous malignant lymphomas (CML) and 41 patients with cutaneous pseudolymphomas (CPL) including chronic actinic dermatitis (CAD) were estimated by DNA flow cytometry. A statistical significant difference between DNA indices (DIs) or proliferative indices (PIs) for CML including mycosis fungoides (MF) II, MF III, Sezary's syndrome (SS), cutaneous peripheral T-cell lymphomas other than MF and SS, cutaneous germinal center cell-derived lymphomas and cutaneous genuine histiocytic lymphoma from CPL. DIs were also helpful in differentiating MF I from CPL. There was a linear relationship between DIs and PIs, both of which had a parallel relationship to the degrees of malignancy and mortality of varieties of CML. The finding of aneuploidy is likely to be useful in differentiating CML from CPL. It is worth noting that DIs, PIs and proportions of aneuploidy in CAD were all higher than those of higher malignancy of CML. These data could not be considered as markers of malignancy.

[Flow cytometer (FCM) in biological characteristics of nasopharyngeal carcinoma xenografts in nude mice].

Tumor tissue from a patient with nasopharyngeal carcinoma was transplanted to nude mice (BALB/c) and had successfully been maintained through ten passages. The nude mice tumor and the primary human tumor were assayed by FCM for the DNA content in addition to conventional pathological examination, chromosome analysis and EBV assay. The tumor incidence in the different passages showed a marked change ranging from 25% to 81% with a mean value of 52% which tended to increase, however. The doubling time of six tumors in the ninth passage showed no great change 6-12 weeks after transplantation with a mean about 4.3 days. But at week 12, there was a significant difference between each tumor volume, ranging from 438 to 1,998 mm3. By FCM, it was found that the DNA index remained constant in both the primary and nude mice tumors. Among the nude mice tumors in different passages, the distribution of various phase cells in cell cycle was similar to that of the primary tumor. In conclusion, the use of FCM to assay the cellular DNA content in nude mice tumor is rapid and sensitive. It is helpful, for the nude mice tumor, in identifying stability of the biological characteristics and in studying of the mechanism of chemotherapy and radiotherapy in the future.