Effects of sika deer on tree seedlings in a warm temperate forest on Yakushima Island,Japan

High-density herbivore species often play an important role in forest regeneration. Native sika deer (Cervus nippon yakushimae) inhabit a high density (51.5–63.8head/km², estimated by a pellet count method) area in the western part of a lowland natural forest on Yakushima Island, Japan. To test experimentally the impact of sika deer on the mortality and the survivability of current-year seedlings, which are at a more vulnerable stage than the later stages, we constructed fenced exclosures, planted seeds of nine sapfruit tree species and compared the mortality and the survivability of current-year seedlings between fenced and unfenced quadrats. Large seeded species had significantly greater survivability in fenced quadrats than in unfenced quadrats. However, the survivability disagreed with feeding preferences. Sika deer activity increased seedling mortality of large-seeded species more than that of small-seeded species, and did not decrease much seedling survivability of not-preferred species. We found that the physical disturbance by the high density of sika deer resulted in mortality for both preferred and not-preferred species, and that deer herbivory was important for preferred species.     

Synthesis of carbamate-type caged derivatives of a novel glutamate transporter blocker

L-threo-beta-Benzyloxyaspartate (L-TBOA) and (2S,3S)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (L-TFB-TBOA) are potent nontransportable blockers for glutamate transporters. We synthesized a carbamate-type coumarin derivative of L-TBOA 3a as a caged blocker and compared 3a with the corresponding ester-type analogs 1. The carbamate 3a was less sensitive to photolysis than the ester 1 but was more stable in the aqueous solution. The [6,7-bis(carboxymethoxy)-coumarin-4-yl]methylcarbonyl (BCMCMC) group exhibited good results both in photoreactivity and stability. Therefore, we examined photolysis of N-BCMCMC-TBOA 3b and N-BCMCMC-TFB-TBOA 4, which immediately released blockers to show glutamate uptake inhibition.     

Reexamination of <Emphasis Type="Italic">Bregmaceros lanceolatus</Emphasis> Shen, 1960 with description of a new species <Emphasis Type="Italic">Bregmaceros pseudolanceolatus</Emphasis> (Gadiformes: Bregmacerotidae)

Based on our reexamination of the 9 specimens including the neotype, Bregmaceros lanceolatus is recharacterized and diagnosed by the following combination of features: caudal fin rounded; scales present on gill cover; dorsal surface of snout unpigmented or with a few chromatophores; isthmus pigmented with punctate chromatophores; two parapophyses on abdominal vertebrae; dorsal rays (D) 65–74; anal rays (A) 67–74; vertebrae (V) 58–61; longitudinal scales (LS) ca. 82–88; principal caudal rays (PC) 16–18; head length (HL)/standard length (SL) 14.0–15.5%; caudal peduncle depth/SL 3.2–4.2%. Based on 27 specimens, B. pseudolanceolatus sp. nov. is described. This species is closely similar to B. lanceolatus, but is diagnosed by the following combination of features: caudal fin rounded; scales present on gill cover; dense concentration of chromatophores on dorsal surface of snout; isthmus colorless; one board-like parapophysis on the last three abdominal vertebrae; D 58–64; A 58–67; V 52–55; LS ca. 68–77; PC 14–16; HL 15.5–18.4% SL; caudal peduncle depth 4.1–5.2% SL. Bregmaceros pseudolanceolatus is known from around the Taiwan Strait, southern East China Sea, South China Sea, Gulf of Thailand, Timor Sea, Arafura Sea, and eastern Bay of Bengal.     

The time of urea treatment and its effects on the succession of ammonia fungi in two warm temperate forests in Japan

We studied the effects of the timing of urea treatment on the succession of ammonia fungi. In two evergreen Castanopsis cuspidata forests and in one deciduous Quercus serrata forest, we applied 343g urea to 25 and 15 plots of 0.5m², respectively, at three different times of the year. Ten of the early-phase (EP) species, considered to be saprotrophic, and 6 of the late-phase (LP) ones, considered ectomycorrhizal, fruited. In both phases, the commencement, peak, and cessation of fruiting took place simultaneously among all the plots treated at the same time. The fruiting occurred in summer and autumn. Quantity and size of the fruit bodies was larger in the LP than in the EP species. Fruiting of EP species was affected by the treatment time and that of LP species by interaction of the treatment time and vegetation type. EP was short and occurred as one period, whereas LP was long and occurred as two or more fruiting seasons. We found that species composition, dominant species, and degree of its dominance in fruiting of the ammonia fungi are predictable for different treatment times of the year and different vegetation types.     

Genetic and linkage analysis of cleistogamy in soybean

Early maturing cultivars of soybean [Glycine max (L.) Merr.] native to the shores of the Sea of Okhotsk (Sakhalin and Kuril Islands) and eastern Hokkaido (northern Japan) have been used in breeding for chilling tolerance. These cultivars have a strong tendency to produce cleistogamous flowers throughout their blooming period. This study was conducted to determine the genetic basis of cleistogamy in an early maturing cultivar, Karafuto-1, introduced from Sakhalin. Genetic analysis was performed using F1 plants, the F2 population, and 50 F3 families produced by crossing between Karafuto-1 and a chasmogamous cultivar, Toyosuzu. F2 plants had chasmogamous flowers, indicating that chasmogamy was dominant to cleistogamy. Analysis of F2 populations and F3 families generated segregation data that was close to a two-gene model with epistatic interactions, although a portion of the pooled F3 data on the frequency of chasmogamous segregants from cleistogamous families significantly deviated from the model. The results suggested that a minimum of two genes with epistatic effects were involved in the genetic control of cleistogamy. Furthermore, cleistogamy was associated with early flowering in the F2 and F3 populations. A gene for cleistogamy was linked to one of the recessive genes responsible for insensitivity to incandescent long daylength.     

Altering the speract-induced ion permeability changes that generate flagellar Ca2+ spikes regulates their kinetics and sea urchin sperm motility

Speract, an egg-derived sperm-activating peptide, induces changes in intracellular Ca2+, Na+, pH, cAMP, cGMP, and membrane potential in sperm of the sea urchin Strongylocentrotus purpuratus. Ca2+ is a key regulator of motility in all sperm and, in many marine species, is required for generating turns interspersed with straighter swimming paths that are essential for chemotaxis towards the egg. We show that speract triggers a train of increases in flagellar Ca2+, and that each individual Ca2+ fluctuation induces a transient increase in flagellar asymmetry that leads to a turn. We also find that modifying the amplitude, duration and interval between individual Ca2+ fluctuations by treating sperm with niflumic acid, an inhibitor of Ca2+-activated Cl(-) channels, correspondingly alters the properties of the sperm turns. We conclude that Ca2+ entry through a fast flagellar pathway not only induces sperm turns, but the kinetics of Ca2+ entry may shape the nature of these turns, and that these kinetics are tuned by other channels, possibly including Cl(-) channels. In addition, the speract-induced changes in sperm motility closely resemble those seen during chemotaxis in other marine organisms, yet speract is not a chemoattractant. This implies the Ca2+-induced motility changes are necessary but not sufficient for chemotaxis.     

CERBERUS, a novel U-box protein containing WD-40 repeats, is required for formation of the infection thread and nodule development in the legume–Rhizobium symbiosis

Endosymbiotic infection of legume plants by Rhizobium bacteria is initiated through infection threads (ITs) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. Despite recent progress in understanding the mutual recognition and early symbiotic signaling cascades in host legumes, the molecular mechanisms underlying bacterial infection processes and successive nodule organogenesis are still poorly understood. We isolated a novel symbiotic mutant of Lotus japonicus , cerberus , which shows defects in IT formation and nodule organogenesis. Map-based cloning of the causal gene allowed us to identify the CERBERUS gene, which encodes a novel protein containing a U-box domain and WD-40 repeats. CERBERUS expression was detected in the roots and nodules, and was enhanced after inoculation of Mesorhizobium loti . Strong expression was detected in developing nodule primordia and the infected zone of mature nodules. In cerberus mutants, Rhizobium colonized curled root hair tips, but hardly penetrated into root hair cells. The occasional ITs that were formed inside the root hair cells were mostly arrested within the epidermal cell layer. Nodule organogenesis was aborted prematurely, resulting in the formation of a large number of small bumps which contained no endosymbiotic bacteria. These phenotypic and genetic analyses, together with comparisons with other legume mutants with defects in IT formation, indicate that CERBERUS plays a critical role in the very early steps of IT formation as well as in growth and differentiation of nodules.