Two Types of Slowly Growing,Nonphotochromogenic Mycobacteria Obtained from Soil by the Mouse Passage Method: Mycobacterium terrae and Mycobacterium novum

Two types of slowly growing, nonphotochromogenic mycobacteria, Mycobacterium terrae and Mycobacterium novum, were isolated from soil by mouse body passage method. The former was presented previously by the present author as a new species. Its characteristics are better clarified in this paper based on the data of 93 strains. Mycobacterium novum is a slowly growing nonphotochromogen. It grows at 10 to 14 days on egg media and does not grow on Sauton agar. It grows on Ogawa egg medium containing either 0.2% (w/v) sodium p-aminosalicylate, 0.1% (w/v) sodium salicylate or 0.25 mg/ml NH₂OH·HCl. It is differentiated from M. tuberculosis, M. bovis and M. microti by these characters. It grows at 28 C and 37 C, but does not grow at 45 C. Other characteristics are: nitrate not reduced; negative two week arylsulphatase; negative niacin test; and no amidase clemonstrated. None of the carbohydrates and nitrogen compounds tested could be utilized as the sole source of carbon or of nitrogen in synthetic agar medium. It survived in mouse organs for three to four weeks. It was noticed that these mycobacteria occur very commonly in soil.     

Two new species of Gelidium (Rhodophyta, Gelidiales), Gelidium tenuifolium and Gelidium koshikianum, from Japan

Two new marine red algae, Gelidium tenuifolium sp. nov. and Gelidium koshikianum sp. nov. (Gelidiales, Gelidiaceae) are described from Japan. Gelidium tenuifolium with large‐sized thalli (up to 30 cm tall) is distinguished from other species with such thalIi by the production of wide, flattened and thin branches (up to 2 mm wide and 60–80 urn thick), the presence of an apical depression and simple determinate branches. Gelidium koshikianum with middle‐sized thalli (5–8 cm tall) is distinguished from other species with such thalli by having wide axes (up to 2.5 mm wide) and short (2.0–3.2 mm), unbranched, second‐ and third‐order branches issuing at short intervals (0.8–1.4 mm). In phylogenetic analyses of rbcL sequences, four Gelidium species that are chiefly distributed in Japan including G. tenuifolium were clustered together with 99% bootstrap value (Japanese Gelidium‐complex clade). Gelidium linoides Kützing came to the position of the sister group to G. tenuifolium with 99% bootstrap value. There were four substitutions (0.3% divergence) between G. linoides and G. tenuifolium sequences. Gelidium koshikianum and Gelidium allanii Chapman were clustered together with 100% bootstrap value and they came to the position of the sister group to the Japanese GeIidium‐complex clade with 83% bootstrap value. There were six substitutions (0.4% divergence) between G. koshikianum and G. allanii sequences.     

New records of Gelidiella pannosa, Pterocladiella caerulescens and Pterocladiella caloglossoides (Rhodophyta, Gelidiales) from Japan

Three gelidialean species, Gelidiella pannosa (Feld‐mann) Feldmann et Hamel, Pterocladiella caerulescens (Kutzing) Santelices et Hommersand and Pterocladiella caloglossoides (Howe) Santelices, are newly reported from Japan, and their characteristic features are described. Monoecious plants of P. caerulescens produce spermatangial sori on: (i) fertile cystocarpic branchlets; (ii) special spermatangial branchlets on a cystocarpic axis; and (iii) branchlets of a special spermatangial axis. The latter two are newly reported in this species. Gelidiella pannosa has numerous unicellular independent points of attachment, whereas P. caerulescens and P. caloglossoides have the peg type of secondary rhizoidal anchorage. In the molecular phylogenetic study using small subunit ribosomal DNA sequences, G. pannosa is included in the Gelidiella clade with 100% bootstrap support in neighbor‐joining (NJ) analysis and 99% in maximum parsimony (MP) analysis. Pterocladiella caerulescens and P. caloglossoides are included in the Pterocladiella clade with 99.7% bootstrap support in NJ analysis and 100% in MP analysis. Each type of secondary rhizoidal attachment is completely consistent with the respective genus clade, which suggests that this morphological characteristic reflects phylogeny within the order Gelidiales.     

Function analysis of steA homolog in Aspergillus oryzae

The asexual ascomycete Aspergillus oryzae has an steA homolog in its genome. The steA homolog of A. oryzae was transcribed in the wild-type strain but steA disruption did not affect the phenotype of the disruptant strain. On the other hand, the steA-overexpressing strain showed the restriction of vegetative hyphal growth and conidiation, and the formation of balloon-shaped structures. The restriction of vegetative hyphal growth and conidiation were partially rescued by high osmolarity. In addition, the hyphal growth of the steA-overexpressing strain was inhibited by Calcofluor white, and the strain was found to be sensitive to cell-wall-degrading reagents. Increase of secretory cell-wall-degrading enzymes of the steA-overexpressing strain was detected. These results indicate that SteA regulates cell-wall-degrading enzymes and that the phenotypes of A. oryzae steA-overexpressing strain may be due to cell wall abnormalities. steA may participate in cell wall metabolism.     

Interactive effects of sublethal predation and body size on siphon production of the bivalve Nuttallia olivacea

This paper is intended to reveal effects of siphon cropping on siphon production of a tellinacean bivalve Nuttallia olivacea, an important prey for juvenile stone flounder. We carried out a two-way field experiment in which bivalves of three treatments (3-times siphon removal, 1-time removal, no removal) and four size classes (9-50 mm shell length) were caged and placed in the field for 3 mo. Growth of repeatedly-removed bivalves was inhibited, indicating reduced siphon growth (natural increase of siphon size according to somatic growth). However, siphon production of removed bivalves was larger than non-removed bivalves, possibly because of siphon regeneration. Juveniles (N. olivacea < 20 mm shell length) showed high growth performance. Their siphon growth was greater than their siphon regeneration. In all bivalves except juveniles, siphon regeneration was greater than siphon growth and engendered high siphon production. Siphon growth was dependent on bivalve size and was only slightly reduced by siphon loss, but siphon regeneration seemed to be dependent mostly on the extent of siphon loss. Greater siphon removal enhanced larger siphon production. These results indicate that intensive siphon cropping by juvenile stone flounder induces high siphon production without serious impact on N. olivacea.     

The structure-function relationship analysis of Prismalin-14 from the prismatic layer of the Japanese pearl oyster, Pinctada fucata

The mollusk shell is a hard tissue consisting of calcium carbonate and organic matrices. The organic matrices are considered to play important roles in shell formation. We have previously identified a prismatic layer-specific protein named Prismalin-14, which consists of 105 amino acid residues and includes four structurally characteristic regions; a repeated sequence of Pro-Ile-Tyr-Arg, a Gly/Tyr-rich region and N- and C-terminal Asp-rich regions. Prismalin-14 showed an inhibitory activity on calcium carbonate precipitation and a calcium-binding ability in vitro. In this study, we prepared some molecular species of recombinant proteins including Prismalin-14 and its truncated proteins in an Escherichia coli expression system to reveal a structure-function relationship of Prismalin-14. The results showed that the Gly/Tyr-rich region was responsible for chitin binding and was identified as a novel chitin-binding sequence. On the other hand, both N- and C-terminal Asp-rich regions are related to inhibitory activity on calcium carbonate precipitation in vitro. Immunohistological observation revealed that Prismalin-14 was localized at the acid-insoluble organic framework including chitin. All these results strongly suggest that Prismalin-14 is a framework protein that mediates chitin and calcium carbonate crystals by using its acidic and chitin-binding regions.     

Hypoxia‐induced localization of chemotaxis‐related signaling proteins in Vibrio cholerae

Vibrio cholerae has three sets of chemotaxis‐related signaling proteins, of which only System II has been shown to be involved in chemotaxis. Here, we examined localization of green fluorescent protein (GFP)‐fused components of System I. The histidine kinase (CheA1) and the adaptor (CheW0) of System I localized to polar and lateral membrane regions with standing incubation (microaerobic conditions), but their localization was lost after shaking (aerobic conditions). A transmembrane receptor of System I also showed polar and lateral localization with standing incubation. By contrast, GFP‐fused components of System II localized constitutively to the flagellated pole. Nitrogen gas, sodium azide or carbonylcyanide m‐chlorophenylhydrazone induced localization of CheA1‐GFP even with shaking incubation, suggesting that the localization is controlled in response to changes in energy metabolism. Fluorescently labeled tetracysteine‐tagged CheA1 also showed azide‐induced localization, arguing against artifactual effects of GFP fusions. These results suggest that System I components are assembled into the supramolecular signaling complex in response to reduced cellular energy states, raising the possibility that the System I complex plays a role in sensing and signaling under microaerobic environments, such as in the host intestine.     

Behavioural mimicry in flight path of Batesian intraspecific polymorphic butterfly Papilio polytes

Batesian mimics that show similar coloration to unpalatable models gain a fitness advantage of reduced predation. Beyond physical similarity, mimics often exhibit behaviour similar to their models, further enhancing their protection against predation by mimicking not only the model''s physical appearance but also activity. In butterflies, there is a strong correlation between palatability and flight velocity, but there is only weak correlation between palatability and flight path. Little is known about how Batesian mimics fly. Here, we explored the flight behaviour of four butterfly species/morphs: unpalatable model Pachliopta aristolochiae, mimetic and non-mimetic females of female-limited mimic Papilio polytes, and palatable control Papilio xuthus. We demonstrated that the directional change (DC) generated by wingbeats and the standard deviation of directional change (SDDC) of mimetic females and their models were smaller than those of non-mimetic females and palatable controls. Furthermore, we found no significant difference in flight velocity among all species/morphs. By showing that DC and SDDC of mimetic females resemble those of models, we provide the first evidence for the existence of behavioural mimicry in flight path by a Batesian mimic butterfly.     

Molecular Dynamics of Channelrhodopsin at the Early Stages of Channel Opening

Channelrhodopsin (ChR) is a light-gated cation channel that responds to blue light. Since ChR can be readily expressed in specific neurons to precisely control their activities by light, it has become a powerful tool in neuroscience. Although the recently solved crystal structure of a chimeric ChR, C1C2, provided the structural basis for ChR, our understanding of the molecular mechanism of ChR still remains limited. Here we performed electrophysiological analyses and all-atom molecular dynamics (MD) simulations, to investigate the importance of the intracellular and central constrictions of the ion conducting pore observed in the crystal structure of C1C2. Our electrophysiological analysis revealed that two glutamate residues, Glu122 and Glu129, in the intracellular and central constrictions, respectively, should be deprotonated in the photocycle. The simulation results suggested that the deprotonation of Glu129 in the central constriction leads to ion leakage in the ground state, and implied that the protonation of Glu129 is important for preventing ion leakage in the ground state. Moreover, we modeled the 13-cis retinal bound; i.e., activated C1C2, and performed MD simulations to investigate the conformational changes in the early stage of the photocycle. Our simulations suggested that retinal photoisomerization induces the conformational change toward channel opening, including the movements of TM6, TM7 and TM2. These insights into the dynamics of the ground states and the early photocycle stages enhance our understanding of the channel function of ChR.