Biology of Asphondyliini (Diptera: Cecidomyiidae)

The family Cecidomyiidae (Diptera) including about 6100 described species displays diverse feeding habits. The tribe Asphondyliini is a well‐circumscribed monophyletic group of Cecidomyiidae and all species are known as gall inducers. Species belonging to this tribe exhibit fascinating ecological traits such as host alternation, polyphagy, extended diapause, induction of dimorphic galls and association with fungal symbionts. For these reasons, biogeographical and phylogenetic studies of Asphondyliini are of interest in elucidating the evolution of these traits, and particularly the processes of host‐range expansion, host‐plant shift and shifts in gall‐bearing organs. In order to facilitate further evolutionary studies of Asphondyliini, I review studies of systematics, biogeography, phylogeny, speciation, cytology, behavior, ecology, physiology, biological interaction and economic importance in this tribe.     

Grazing on toxic cyanobacterial blooms by tadpoles of edible frog Rana grylio

Tadpoles of Rana grylio were raised as edible frogs in fishponds of Guanqiao in Wuhan City, Hubei, China, during cyanobacterial blooms from June to October. The dominant cyanobacterial species was Microcystis, which was found to be lethally toxic by intraperitoneal (i.p.) mouse bioassay. Little is known about the effect of tadpoles on toxic cyanobacterial blooms. To evaluate the potential of the tadpoles to graze on cyanobacterial blooms, the tadpoles were fed on Microcystis collected from the field in the laboratory. The Microcystis cells decreased from 1.19 × 10⁷ cells mL^?1 to 3.23 × 10⁶ cells mL^?1, with a sharp reduction of 73% of the initial Microcystis population observed in the first 24 h after introduction of the tadpoles. The ponds containing tadpoles had a markedly lower density of Microcystis than those lacking tadpoles. Tadpoles exposed to either cultured Microcystis aeruginosa (NIES–90, 2.768 µg microcystins mg^–1 dw^–1) cells or lysed M. aeruginosa cells grew well, however, indicating that they were unaffected by Microcystis toxins. We found a significant increase in tadpole body weight after feeding on either field Microcystis or cultured M. aeruginosa. The mean increase in individual body weight was 20 mg day^?1 when fed on Microcystis from the pond, and 7 mg day^?1 when fed on M. aeruginosa from culture. Our study strongly suggested that there is a direct trophic relationship between R. grylio tadpoles and toxic Microcystis blooms and they possess the potential to graze on toxic Microcystis. The results imply that R. grylio tadpoles may play an important ecological role in reducing toxic cyanobacterial blooms caused by Microcystis.     

Life cycle of Chattonella marina (Raphidophyceae) inferred from analysis of microsatellite marker genotypes

Red tides of Chattonella spp. have caused continuous damage to Japanese aquaculture, however, the life cycle of this organism remains incompletely understood. To further investigate this matter, we assessed genotypes at 14 microsatellite markers in three varieties of Chattonella marina, viz., C. marina var. antiqua, C. marina var. marina, and C. marina var. ovata, to establish whether Chattonella undergoes asexual diploidization or sexual reproduction. After genotyping 287 strains of C. marina, all but one of these strains was shown to be heterozygous for at least some loci, and thus, in the diploid state, suggesting that Chattonella strains undergo sexual reproduction. In addition, we performed single‐cell amplification on ‘small cells’ that are derived from vegetative cells under dark and low‐nutrient conditions. The results indicated the existence of two types of small cells. The ‘Small cell Type 1’ was found to be heterozygous, genotypically equivalent to the vegetative cells, and is therefore diploid. These small cells may change to resting cells (cysts) directly. The ‘Small cell Type 2’ was homozygous at all analyzed loci, suggesting that these small cells are haploid and may be derived by meiosis. As fusion between small cells has previously been observed, the ‘Small cell Type 2’ may be the gamete of Chattonella. We present a construct of the full life cycle of Chattonella marina based on our own and previous results.     

Evidence of the existence of a toxic form of Cylindrospermopsis raciborskii (Nostocales,Cyanobacteria) in Japan

Cylindrospermopsis raciborskii is a common, bloom‐forming, planktonic, freshwater cyanobacterium. Toxic populations producing cylindrospermopsin can cause water‐safety problems. Although C. raciborskii is distributed worldwide, the presence of cylindrospermopsin‐producing strains of C. raciborskii was initially reported only in Australia and recently in Thailand. Here, we report the isolation of a toxic strain of C. raciborskii (ISG9) from a freshwater sample collected in Okinawa in 2008. This is the first report describing toxin expression in this species in Japan, detected from a subtropical area. The C. raciborskii species is known to produce cylindrospermopsin as a dominant toxin; however, in this new isolate, the dominant toxin expressed was deoxy‐cylindrospermopsin. The discovery of a toxic strain of C. raciborskii in southern Japan emphasizes the need for basic monitoring schemes for this species in water supplies located in the temperate regions of Japan because of its possible expansion and distribution to other geographic areas.     

Large-scale development of expressed sequence tag-derived simple sequence repeat markers and diversity analysis in Arachis spp.

Large-scale development of expressed sequence tag simple sequence repeat (EST-SSR) markers was performed in peanut (Arachis hypogaea L.) to obtain more informative genetic markers. A total of 10,102 potential non-redundant EST sequences, including 3,445 contigs and 6,657 singletons, were generated from cDNA libraries of the gynophore, roots, leaves and seedlings. A total of 3,187 primer pairs were designed on flanking regions of SSRs, some of which allowed one and two base mismatches. Among the 3,187 markers generated, 2,540 (80%) were trinucleotide repeats, 302 (9%) were dinucleotide repeats, and 345 (11%) were tetranucleotide repeats. Pre-polymorphic analyses of 24 Arachis accessions were performed using 10% polyacrylamide gels. A total of 1,571 EST-SSR markers showing clear polymorphisms were selected for further polymorphic analysis with a Fluoro-fragment Analyzer. The 16 Arachis accessions examined included cultivated peanut varieties as well as diploid species with the A or B genome. Altogether 1,281 (81.5%) of the 1,571 markers were polymorphic among the 16 accessions, and 366 (23.3%) were polymorphic among the 12 cultivated varieties. Diversity analysis was performed and the genotypes of all 16 Arachis accessions showed similarity coefficients ranging from 0.37 to 0.97. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11032-011-9604-8) contains supplementary material, which is available to authorized users.     

Impact of medium volume and oxygen concentration in the incubator on pericellular oxygen concentration and differentiation of murine chondrogenic cell culture

Previous studies have demonstrated that oxygen environment is an important determinate factor of cell phenotypes and differentiation, although factors which affect pericellular oxygen concentration (POC) in murine chondrogenic cell culture remain unidentified. Oxygen concentrations in vivo were measured in rabbit musculoskeletal tissues, which were by far hypoxic compared to 20% O₂ (ranging from 2.29 ± 1.16 to 4.36 ± 0.51%). Oxygen concentrations in murine chondrogenic cell (C3H10T1/2) culture medium were monitored in different oxygen concentrations (20% or 5%) in the incubator and in different medium volumes (3,700 or 7,400 μl) within 25-cm² flasks. Chondrogenic differentiation was assessed by glycosaminoglycan production with quantitative evaluation of Alcian blue staining in 12-well culture dishes. Expression of chondrogenic genes, aggrecan, and type II collagen α1, was examined by quantitative real-time polymerase chain reaction. Oxygen concentrations in medium decreased accordingly with the depth from medium surface, and POC at Day 6 was 18.99 ± 0.81% in 3,700-μl medium (1,480-μm depth) and 13.26 ± 0.23% in 7,400-μl medium (2,960-μm depth) at 20% O₂ in the incubator, which was 4.96 ± 0.08% (1,480-μm depth) and 2.83 ± 0.42% (2,960-μm depth) at 5% O₂, respectively. The differences of POC compared by medium volume were statistically significant (p = 0.0003 at 20% and p = 0.001 at 5%). Glycosaminoglycan production and aggrecan gene expression were most promoted when cultured in moderately low POC, 1,000 μl (2,960-μm depth) at 20% O₂ and 500 μl (1,480-μm depth) at 5% O₂ in 12-well culture dishes. We demonstrate that medium volume and oxygen concentration in the incubator affect not only POC but also chondrogenic differentiation.     

DNA damage signaling triggers degradation of histone methyltransferases through APC/C(Cdh1) in senescent cells

Both the DNA damage response (DDR) and epigenetic mechanisms play key roles in the implementation of senescent phenotypes, but very little is known about how these two mechanisms are integrated to establish senescence-associated gene expression. Here we show that, in senescent cells, the DDR induces proteasomal degradation of G9a and GLP, major histone H3K9 mono- and dimethyltransferases, through Cdc14B- and p21(Waf1/Cip1)-dependent activation of APC/C(Cdh1) ubiquitin ligase, thereby causing a global decrease in H3K9 dimethylation, an epigenetic mark for euchromatic gene silencing. Interestingly, induction of IL-6 and IL-8, major players of the senescence-associated secretory phenotype (SASP), correlated with a decline of H3K9 dimethylation around the respective gene promoters and knockdown of Cdh1 abolished IL-6/IL-8 expression in senescent cells, suggesting that the APC/C(Cdh1)-G9a/GLP axis plays crucial roles in aspects of senescent phenotype. These findings establish a role for APC/C(Cdh1) and reveal how the DDR integrates with epigenetic processes to induce senescence-associated gene expression.     

The development of a canine anorectal autotransplantation model based on blood supply: a preliminary case report

Colostomy is conventionally the only treatment for anal dysfunction. Recently, a few trials of anorectal transplantation in animals have been published; however, further development of this technique is required. Moreover, it is crucial to perform this research in dogs, which resemble humans in anorectal anatomy and biology. We designed a canine anorectal transplantation model, wherein anorectal autotransplantation was performed by anastomoses of the rectum, inferior mesenteric artery (IMA) and vein, and pudendal nerves. Resting pressure in the anal canal and anal canal pressure fluctuation were measured before and after surgery. Graft pathology was examined three days after surgery. The anal blood supply was compared with that in three beagles using indocyanine green (ICG) fluorescence angiography. The anorectal graft had sufficient arterial blood supply from the IMA; however, the graft's distal end was congested and necrotized. Functional examination demonstrated reduced resting pressure and the appearance of an irregular anal canal pressure wave after surgery. ICG angiography showed that the pudendal arteries provided more blood flow than the IMA to the anal segment. This is the first canine model of preliminary anorectal autotransplantation, and it demonstrates the possibility of establishing a transplantation model in dogs using appropriate vascular anastomoses, thus contributing to the progress of anorectal transplantation.