Kanzaki N (2016) PLoS One "Stomatal Dimorphism of Neodiplogaster acaloleptae (Diplogastromorpha: Diplogastridae)."

Kanzaki N

[PLoS One, 2016]

Several genera belonging to the nematode family Diplogastridae show characteristic dimorphism in their feeding structures; specifically, they have microbial feeding stenostomatous and predatory eurystomatous morphs. A diplogastrid satellite model species, Pristionchus pacificus, and its close relatives have become a model system for studying this phenotypic plasticity, with intensive physiological and structural studies having been undertaken. However, the many other species that are morphologically and phylogenetically divergent from P. pacificus have not been examined to date. In the present study, the detailed stomatal structure and induction of dimorphism in Neodiplogaster acaloleptae were examined. N. acaloleptae has a fungal feeding stenostomatous morph and a predatory eurystomatous morph. The predatory morph was induced by starvation, high population density, and co-culturing with its potential prey, Caenorhabditis elegans. The feeding behavior of the stenostomatous and eurystomatous morphs of N. acaloleptae was confirmed, demonstrating that 1) the stomatal and pharyngeal movements of the two morphs were basically identical, and 2) the stomatal elements were protracted to cut open the hyphae and/or prey to feed when a N. acaloleptae flips its dorsal movable tooth dorsally and tilts its subventral stegostomatal cylinder ventrally, forming a pair of scissors to cut the food source. The stoma morphology of N. acaloleptae with a single movable tooth and a long stoma is markedly different from that of Pristionchus, which has two movable teeth and a short stoma. It is, however, similar to that of Mononchoides, tentatively a sister to Neodiplogaster.

Kanzaki N et al. (2018) Nat Commun "Biology and genome of a newly discovered sibling species of Caenorhabditis elegans."

Kikuchi T, Hunt VL, Liu D, Tsai IJ, Ke HM, Chai C, Akagi A, Wang J, Murase K, Kanzaki N, Tsuyama K, Maeda Y, Woodruff GC, Sternberg PW, Kitazume H, Sugimoto A, Kumagai R, Namai S, Holroyd N, Doyle SR, Panda O, Berriman M, Tracey A, Tanaka R, Schroeder FC

[Nat Commun, 2018]

A 'sibling' species of the model organism Caenorhabditis elegans has long been sought for use in comparative analyses that would enable deep evolutionary interpretations of biological phenomena. Here, we describe the first sibling species of C. elegans, C. inopinata n. sp., isolated from fig syconia in Okinawa, Japan. We investigate the morphology, developmental processes and behaviour of C. inopinata, which differ significantly from those of C. elegans. The 123-Mb C. inopinata genome was sequenced and assembled into six nuclear chromosomes, allowing delineation of Caenorhabditis genome evolution and revealing unique characteristics, such as highly expanded transposable elements that might have contributed to the genome evolution of C. inopinata. In addition, C. inopinata exhibits massive gene losses in chemoreceptor gene families, which could be correlated with its limited habitat area. We have developed genetic and molecular techniques for C. inopinata; thus C. inopinata provides an exciting new platform for comparative evolutionary studies.

Kanzaki N et al. (2013) J Nematol "Pristionchus bucculentus n. sp. (Rhabditida: Diplogastridae) Isolated from a Shining Mushroom Beetle (Coleoptera: Scaphidiidae) in Hokkaido, Japan."

Roseler W, Kanzaki N, Sommer RJ, Herrmann M, Ragsdale EJ

[J Nematol, 2013]

Pristionchus bucculentus n. sp. was isolated from a shining mushroom beetle, Episcapha gorhami, associated with white rot on a decaying log in Hokkaido, Japan. The new species is distinguished by its stomatal morphology, which includes three regularly shaped, conical left subventral denticles and a vacuolated cheilostom with weak internal sclerotization. Also distinguishing P. bucculentus n. sp. are male sexual characters, including arrangement of genital papillae, a rounded and ventrally skewed manubrium, and a gubernaculum with a large, deep posterior curvature and a short, shallow anterior curvature. Morphological and molecular evidence support the new species as being close to P. elegans, which was previously the most basal known species of the genus. Comparative morphology of basal Pristionchus species is supported by a molecular phylogeny inferred from a partial small subunit ribosomal rRNA gene and 25 ribosomal protein-coding genes. Description of P. bucculentus n. sp. provides a new point of comparison for reconstructing the evolution of stomatal characters in the comparative model system of Pristionchus.

Kanzaki N et al. (2012) J Nematol "Two New Species of Pristionchus (Rhabditida: Diplogastridae): P. fissidentatus n. sp. from Nepal and La Reunion Island and P. elegans n. sp. from Japan."

Ragsdale EJ, Herrmann M, Kanzaki N, Sommer RJ

[J Nematol, 2012]

Pristionchus fissidentatus n. sp., isolated from soil in Nepal, and n. sp., isolated from (Coleoptera: Scarabaeidae) in Japan, are described. The two new species are recognized as basal within the genus and thus occupy an important position for macroevolutionary studies that center on the model . n. sp. is distinguished by its unique stegostomatal morphology: in the stenostomatous form, the right subventral ridge has three prominent cusps and the left subventral sector has, in addition to a plate with two cusps, a prominent denticle slightly left of ventral; in the eurystomatous form, the right subventral stegostomatal sector shows both a tooth and a ridge with several cusps. Diagnostic of n. sp. is the structure of the stenostomatous cheilostom, which bulges medially and is underlain by a large vacuolated ring. No eurystomatous form has been observed in n. sp. Reproductive modes of n. sp. and n. sp. are hermaphroditic and gonochoristic, respectively. The additional isolation of n. sp. from soil and two species of scarab beetle on La Reunion Island in the Indian Ocean suggests a broad geographic range for this species.

Herrmann M et al. (2019) J Nematol "Two new Species of Pristionchus (Nematoda: Diplogastridae) include the Gonochoristic Sister Species of P. fissidentatus."

Kanzaki N, Yoshida K, Weiler C, Herrmann M, ROdelsperger C, Sommer RJ

[J Nematol, 2019]

The genus <i>Pristionchus</i> (Kreis, 1932) consists of more than 30 soil nematode species that are often found in association with scarab beetles. Three major radiations have resulted in the &quot;<i>maupasi</i> species group&quot; in America, the &quot;<i>pacificus</i> species group&quot; in Asia, and the &quot;<i>lheritieri</i> species group,&quot; which contains species from Europe and Asia. Phylogenetic analysis indicates that a group of three species, including the gonochorists <i>P. elegans</i> and <i>P. bucculentus</i> and the hermaphrodite <i>P. fissidentatus</i>, is basal to the above-mentioned radiations. Two novel species are described here: <i>Pristionchus paulseni</i> sp. n. from Taiwan and <i>P. yamagatae</i> sp. n. from Japan by means of morphology, morphometrics and genome-wide transcriptome sequence analysis. Previous phylotranscriptomic analysis of the complete <i>Pristionchus</i> genus recognized <i>P. paulseni</i> sp. n. as the sister species of <i>P. fissidentatus</i>, and thus its importance for macro-evolutionary studies. Specifically, the gonochorist <i>P. paulseni</i> sp. n. and the hermaphrodite <i>P. fissidentatus</i> form a species pair that is the sister group to all other described <i>Pristionchus</i> species. <i>P. paulseni</i> sp. n. has two distinct mouth forms, supporting the notion that the mouth dimorphism is ancestral in the genus <i>Pristionchus</i>.

Ragsdale E et al. (2015) "Taxonomy and natural history: the genus Pristionchus"

Kanzaki N, Ragsdale E, Herrmann M

[2015]

Ge YL et al. (2002) Anticancer Res "Effects of adenoviral gene transfer of C. elegans n-3 fatty acid desaturase on the lipid profile and growth of human breast cancer cells."

Kang ZB, Chen Z, Leaf A, Kang JX, Cluette-Brown J, Laposata M, Ge YL

[Anticancer Res, 2002]

Background: Current evidence from both experimental and human studies indicates that omega-6 polyunsaturated fatty acids (n-6 PUFAs) promote breast tumor development, whereas long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) exert suppressive effects. The ratio of n-6 to n-3 fatty acids appears to be an important factor in controlling tumor development. Human cells usually have a very high n-6/n-3 fatty acid ratio because they cannot convert n-6 PUFAs to n-3 PUFAs due to lack of an n-3 desaturase found in C. elegans. Materials and Methods: Adenoviral strategies were used to introduce the C. elegans fat-1 gene encoding an n-3 fatty acid desaturase into human breast cancer cells followed by examination of the n-6/n-3 fatty acid ratio and growth of the cells. Results: Infection of MCF-7 cells with an adenovirus carrying the fat-1 gene resulted in a high expression of the n-3 fatty acid desaturase. Lipid analysis indicated a remarkable increase in the levels of n-3 PUFAs accompanied with a large decrease in the contents of n-6 PUFAs, leading to a change of the n-6/n-3 ratio from 12.0 to 0.8. Accordingly, production of the eicosanoids derived from n-6 PUFA was reduced significantly in cells expressing the fat-1 gene. Importantly, the gene transfer induced mass cell death and inhibited cell proliferation. Conclusion: The gene transfer of the n-3 fatty acid desaturase, as a novel approach, can effectively modify the n-6/n-3 fatty acid ratio of human tumor cells and provide an anticancer effect, without the need of exogenous n-3 PUFA supplementation. These data also increase the understanding of the effects of n-3 fatty acids and the n-6/n-3 ratio on cancer prevention and treatment.

Susoy V et al. (2015) Elife "Rapid diversification associated with a macroevolutionary pulse of developmental plasticity."

Ragsdale EJ, Kanzaki N, Sommer RJ, Susoy V

[Elife, 2015]

Developmental plasticity has been proposed to facilitate phenotypic diversification in plants and animals, but the macroevolutionary potential of plastic traits remains to be objectively tested. We studied the evolution of feeding structures in a group of 90 nematodes, including Caenorhabditis elegans, some species of which have evolved a mouthpart polyphenism, moveable teeth, and predatory feeding. Comparative analyses of shape and form, using geometric morphometrics, and of structural complexity revealed a rapid process of diversification associated with developmental plasticity. First, dimorphism was associated with a sharp increase in complexity and elevated evolutionary rates, represented by a radiation of feeding-forms with structural novelties. Second, the subsequent assimilation of a single phenotype coincided with a decrease in mouthpart complexity but an even stronger increase in evolutionary rates. Our results suggest that a macroevolutionary 'pulse' of plasticity promotes novelties and, even after the secondary fixation of phenotypes, permits sustained rapid exploration of morphospace.

Tanaka, R. et al. (2013) International Worm Meeting "Quiescence of entomo-phoretic nematode Caenorhabditis japonica."

Kanzaki, N., Hirooka, Y., Kikuchi, T., Tanaka, R.

[International Worm Meeting, 2013]

Entomo-phoretic nematodes are not parasitic to insects but use insects for their transportation. Caenorhabditis japonica, a bacteria-feeding nematode, has a species-specific phoresy with a shield bug, Parastrachia japonensis, and its lifecycle is synchronized to the bug's life. The active dauer larvae (DL) show intensive host-seeking, high sensitivity to oxidative stress and less than 15 days of longevity without attaching the bug. On the other hand, quiescent DL on the bug survive more than 11 months. Thus, the quiescence associated with the bug seems an essential factor for nematode survivability. In the present study, survivabilities of quiescent and active DL were compared under several different conditions to examine the involvement of the bugs in nematode's longevity. Then transcripts and proteins were analyzed to compare gene expression between quiescent and active DL. The quiescent DL on the bug and active DL were kept in a container with 85% (dehydrated condition) or 97% (lightly dehydrated condition which immobilize the DL) of relative humidity (RH). The most active DL died in one week because of desiccation (85% RH) or fungal infection (97% RH). On the other hands, quiescent DL on the bug showed significantly higher survival rate under the same conditions. Further, the survivability of surface-sterilized active DL kept in 97% RH was almost the same as quiescent DL. Therefore, the bugs are likely to work as the shelter from dehydration, and are also providing anti-microbe activity to DL. The expressed genes and proteins also differed between quiescent and active DL. Expression of genes and proteins involved in several stress resistance, metabolic regulation and cuticle formation were significantly higher in quiescent DL. On the other hand, expression of genes and proteins involved in several metabolic related (activity regulation) were significantly higher in active DL. Our results suggest C. japonica DL use their host bug not only for transportation, but also as shelter from environmental stresses and microbe infection. Further, the quiescent stage-specific gene expression allows the extraordinary longevity of this stage.

Seo J et al. (2005) Arch Environ Contam Toxicol "Biodegradation of the insecticide N,N-diethyl-m-toluamide by fungi: identification and toxicity of metabolites."

Kim SD, Cha CJ, Hur HG, Lee YG, Seo J, Ahn JH

[Arch Environ Contam Toxicol, 2005]

Fungi (Cunninghamella elegans ATCC 9245, Mucor ramannianus R-56, Aspergillus niger VKMF-1119, and Phanerochaete chrysosporium BKMF-1767) were tested to elucidate the biologic fate of the topical insect repellent N,N-diethyl-m-toluamide (DEET). The elution profile obtained from analysis by high-pressure liquid chromatography equipped with a reverse-phase C-18 column, showed that three peaks occurred after incubation of C. elegans, with which 1 mM DEET was combined as a final concentration. The peaks were not detected in the control experiments with either DEET alone or tested fungus alone. The metabolites produced by C. elegans exhibited a molecular mass of 207 with a fragment ion (m/z) at 135, a molecular mass of 179 with an m/z at 135, and a molecular mass of 163 with an m/z at 119, all of which correspond to N,N-diethyl-m-toluamide-N-oxide, N-ethyl-m-toluamide-N-oxide, and N-ethyl-m-toluamide, respectively. M. ramannianus R-56 also produced N, N-diethyl-m-toluamide-N-oxide and N-ethyl-m-toluamide but did not produce N-ethyl-m-toluamide-N-oxide. For the biologic toxicity test with DEET and its metabolites, the freshwater zooplankton Daphnia magna was used. The biologic sensitivity in decreasing order was DEET > N-ethyl-m-toluamide > N,N-diethyl-m-toluamide-N-oxide. Although DEET and its fungal metabolites showed relatively low mortality compared with other insecticides, the toxicity was increased at longer exposure periods. These are the first reports of the metabolism of DEET by fungi and of the biologic toxicity of DEET and its fungal metabolites to the freshwater zooplankton D. magna.