Role of Chitinase and Chitin Oligosaccharides in Lignification Response of Cultured Carrot Cells Treated with Mycelial Walls

Chitinase activity was induced in cultured carrot cells by incubationwith mycelial walls of a fungus, Chaetomium globosum. Both intra-and extracellular chitinases were resolved into four componentsby gel filtration chromatography. The extracellular enzymesliberated soluble oligosaccharides of different sizes from insolublechitin, suggesting that these carrot chitinases are endo-hydrolases.The solubilized chitinase digests obtained from insoluble mycelialwalls of C. globosum and chitin were fractionated by gel filtrationchromatography, and the elicitor activity of each fraction forthe accumulation of phenolic acids in cultured carrot cellswas determined. In both solubilized fragments of fungal wallsand of chitin, elicitor-active oligosaccharides were distributedin many fractions, however, potent activity for inducing phenolicacid synthesis was observed in the high molecular weight fractions. (Received October 5, 1987; Accepted February 12, 1988)     

Systematic revision of the catfish genusSilurus,with description of a new species from Thailand and Burma

On the basis of external morphology and anatomy, 17 scpeies of the genusSilurus Linnaeus including a new species,S. torrentis from Thailand and Burma, are recognized as valid.S. bedfordi Regan is synonymized withS. asotus, andS. goae Haig is transferred to the genusOmpok. From an anatomical study of 12 species, the diagnostic feature of the genusParasilurus Bleeker is revealed to be invalid, and the genus is synonymized withSilurus. From the phylogenetic analysis, the genusSilurus is divided into two major species groups, thecochinchinensis group which is disributed mainly in Southeast Asia, and theglanis group which is further separated into three subgroups occurring separately in East Asia and Europe. The pattern of distribution and relationships between ontogeny and phytogeny in the genusSilurus are briefly discussed.     

Comparative morphology and development of bony elements in the head region in three species of Japanese catfishes (Silurus: Siluridae; Siluriformes)

The shape and development of bony elements of the neurocranium and suspensorium were studied in three species of Japanese catfish (Silurus) from the viewpoint of comparative morphology. InS. asotus andS. biwaensis the order of appearance of the bony elements was similar, but the ossification of most elements was delayed inS. lithophilus. The neurocranium and Suspensorium of adultS. lithophilus retain juvenile features compared with the other two species. On the other hand, in the skull ofS. biwaensis the sagittal crest of the supraoccipital, the ridge of the pterotic, and the hyomandibular process are more developed than in the other two species.     

A Novel Alveolate in Bivalves with Chemosynthetic Bacteria Inhabiting Deep‐Sea Methane Seeps

It has recently been unveiled that a wide variety of microbial eukaryotes (protists) occur in chemosynthetic ecosystems, such as hydrothermal vents and methane seeps. However, there is little knowledge regarding protists associated with endemic animals inhabiting these environments. In the present study, utilizing PCR techniques, we detected fragments of the small subunit ribosomal RNA gene (SSU rRNA gene) from a particular protist from gill tissues of a significant fraction of the vesicomyid clams Calyptogena soyoae and C. okutanii complex and of the mussel Bathymodiolus platifrons and B. japonicus, all of which harbor chemosynthetic endosymbiont bacteria and dominate methane seeps in Sagami Bay, Japan. Based on the phylogeny of SSU rRNA gene, the organism in question was shown to belong to Alveolata. It is noteworthy that this protist did not affiliate with any known alveolate group, although being deeply branched within the lineage of Syndiniales, for which the monophyly was constantly recovered, but not robustly supported. In addition, the protist detected using PCR followed by sequencing was localized within gill epithelial cells of B. platifrons with whole‐mount fluorescence in situ hybridization. This protist may be an endoparasite or an endocommensal of Calyptogena spp. and Bathymodiolus spp., and possibly have physiological and ecological impacts on these bivalves.     

Inhibition of Binding of Tomato Yellow Leaf Curl Virus Rep to its Replication Origin by Artificial Zinc-Finger Protein

Previously we demonstrated that inhibition of replication-associated protein (Rep) binding to its replication origin by artificial zinc-finger proteins (AZPs) is a powerful method to prevent plant virus infection in vivo. In the present study, we applied the AZP technology to Tomato yellow leaf curl virus (TYLCV), which is a limiting factor in tomato cultivation worldwide. First, we determined 5′-ATCGGTGT ATCGGTGT-3′ in the 195-bp intergenic region of the TYLCV-Israel strain, a strain reported first among TYLCV strains, as the Rep-binding site by gel shift assays. We then constructed a 6-finger AZP that bound to a 19-bp DNA including the Rep-binding site. We demonstrated that the binding affinity of the AZP was >1,000-fold greater than that of Rep and that the AZP inhibited Rep binding completely in vitro. Because the binding capability of the AZP was same as that of the AZP previously designed for geminivirus-resistant Arabidopsis thaliana, we predict that the present AZP will prevent TYLCV infection in vivo.     

Active Sensing System with In Situ Adjustable Sensor Morphology

Background

Despite the widespread use of sensors in engineering systems like robots and automation systems, the common paradigm is to have fixed sensor morphology tailored to fulfill a specific application. On the other hand, robotic systems are expected to operate in ever more uncertain environments. In order to cope with the challenge, it is worthy of note that biological systems show the importance of suitable sensor morphology and active sensing capability to handle different kinds of sensing tasks with particular requirements.

Methodology

This paper presents a robotics active sensing system which is able to adjust its sensor morphology in situ in order to sense different physical quantities with desirable sensing characteristics. The approach taken is to use thermoplastic adhesive material, i.e. Hot Melt Adhesive (HMA). It will be shown that the thermoplastic and thermoadhesive nature of HMA enables the system to repeatedly fabricate, attach and detach mechanical structures with a variety of shape and size to the robot end effector for sensing purposes. Via active sensing capability, the robotic system utilizes the structure to physically probe an unknown target object with suitable motion and transduce the arising physical stimuli into information usable by a camera as its only built-in sensor.

Conclusions/Significance

The efficacy of the proposed system is verified based on two results. Firstly, it is confirmed that suitable sensor morphology and active sensing capability enables the system to sense different physical quantities, i.e. softness and temperature, with desirable sensing characteristics. Secondly, given tasks of discriminating two visually indistinguishable objects with respect to softness and temperature, it is confirmed that the proposed robotic system is able to autonomously accomplish them. The way the results motivate new research directions which focus on in situ adjustment of sensor morphology will also be discussed.     

Ly6C+Ly6G− Myeloid‐derived suppressor cells play a critical role in the resolution of acute inflammation and the subsequent tissue repair process after spinal cord injury

Acute inflammation is a prominent feature of central nervous system (CNS) insult and is detrimental to the CNS tissue. Although this reaction spontaneously diminishes within a short period of time, the mechanism underlying this inflammatory resolution remains largely unknown. In this study, we demonstrated that an initial infiltration of Ly6C⁺Ly6G^? immature monocyte fraction exhibited the same characteristics as myeloid‐derived suppressor cells (MDSCs), and played a critical role in the resolution of acute inflammation and in the subsequent tissue repair by using mice spinal cord injury (SCI) model. Complete depletion of Ly6C⁺Ly6G^? fraction prior to injury by anti‐Gr‐1 antibody (clone: RB6‐8C5) treatment significantly exacerbated tissue edema, vessel permeability, and hemorrhage, causing impaired neurological outcomes. Functional recovery was barely impaired when infiltration was allowed for the initial 24 h after injury, suggesting that MDSC infiltration at an early phase is critical to improve the neurological outcome. Moreover, intraspinal transplantation of ex vivo‐generated MDSCs at sites of SCI significantly reduced inflammation and promoted tissue regeneration, resulting in better functional recovery. Our findings reveal the crucial role of an Ly6C⁺Ly6G^? fraction as MDSCs in regulating inflammation and tissue repair after SCI, and also suggests an MDSC‐based strategy that can be applied to acute inflammatory diseases.     

Enhanced accumulation of atropine in Atropa belladonna transformed by Rac GTPase gene isolated from Scoparia dulcis

Leaf tissues of Atropa belladonna were transformed by Sdrac2, a Rac GTPase gene, that is isolated from Scoparia dulcis, and the change in atropine concentration of the transformants was examined. Re-differentiated A. belladonna overexpressing Sdrac2 accumulated considerable concentration of atropine in the leaf tissues, whereas the leaves of plants transformed by an empty vector accumulated only a very low concentration of the compound. A. belladonna transformed by CASdrac2, a modified Sdrac2 of which translate was expected to bind guanosine triphosphate (GTP) permanently, accumulated very high concentrations of atropine (approximately 2.4-fold excess to those found in the wild-type plant in its natural habitat). In sharp contrast, the atropine concentration in transformed A. belladonna prepared with negatively modified Sdrac2, DNSdrac2, expected to bind guanosine diphosphate instead of GTP, was very low. These results suggested that Rac GTPases play an important role in the regulation of secondary metabolism in plant cells and that overexpression of the gene(s) may be capable of enhancing the production of natural products accumulated in higher plant cells.     

Gustatory evoked cortical activity in humans studied by simultaneous EEG and MEG recording

Evoked potentials are widely used in clinical medicine for objective evaluation of sensory disturbances. However, gustatory evoked potentials (GEPs) have not been extensively studied due to lack of agreement among investigators regarding the waveforms. In this study GEPs and gustatory magnetic fields (GEMfs) were simultaneously recorded from five subjects in response to 0.3 M NaCl in an attempt to establish GEP recording as an objective gustatometer. Each subject received a total of 240 stimulus presentations over six sessions. Three GEP components (P1, N1 and P2) were observed and correlated with their corresponding equivalent current dipoles (ECD1, ECD2 and ECD3, respectively). ECD1 was localized to area G in all subjects, P1 being the indicator of intact gustatory projection to area G. No significant GEP activity was detected during the time preceding P1, which suggests that there was no activity in cortical gyri other than that detected by magnetoencephalography. ECD2 and ECD3 were localized to various cortical structures, including the inferior insula and the superior temporal sulcus, indicating that N1 and P2 reflect higher order gustatory functions. The present results indicate that measurement of GEPs may be useful for objective evaluation of gustatory disturbance.     

Foot formation in hydra: commitment of the basal disk cells in the lower peduncle

Foot regeneration in the freshwater hydra Pelmatohydra robusta was examined using a monoclonal antibody AE03 as a marker. This antibody specifically recognizes mucous-producing ectodermal epithelial cells in the basal disk, but not cells in the peduncle region located just above the basal disk in the foot. When the basal disk was removed by amputation at the upper or lower part of the peduncle, AE03-positive (basal disk) cells always appeared at the regenerating tip of the footless polyp approximately 12-16 h later. When a small piece of tissue was cut out from the upper or lower peduncle region, the tissue invariably turned into a smooth spherical or oblong shape within a few hours. AE03 signal appeared in these spheres variably depending on their origin: when tissue pieces were derived from the lower peduncle, the signal appeared in nearly all pieces and often covered the entire surface of the pieces within 24 h. In contrast, the signal appeared in less than 10% of pieces derived from the upper peduncle. Furthermore, the signal seldom covered more than half of the surface of these pieces. When maintained for many days, pieces derived from the upper peduncle often regenerated tentacles, whereas those from the lower peduncle seldom did. These and other observations suggest that epithelial cells in the peduncle can rapidly differentiate into basal disk cells when the basal tissue is removed. However, cells in the upper peduncle are not irreversibly committed to differentiate into basal disk cells because, when cut out as small tissue pieces, they could remain AE03 negative and become tentacle cells. In contrast, the cells in the lower peduncle apparently are irreversibly committed to differentiate into basal disk cells, as they always turned rapidly into AE03-positive cells once they were physically separated from (and freed from the influence of) the basal disk itself, regardless of the separation methods used.