Reversible molecular adsorption based on multiple-point interaction by shrinkable gels

A general approach is presented for creating polymer gels that can recognize and capture a target molecule by multiple-point interaction and that can reversibly change their affinity to the target by more than one order of magnitude. The polymers consist of majority monomers that make the gel reversibly swell and shrink and minority monomers that constitute multiple-point adsorption centers for the target molecule. Multiple-point interaction is experimentally proven by power laws found between the affinity and the concentration of the adsorbing monomers within the gels.     

Effect of parthenocarpy,peeling and fruit age on the changes in volume and specific gravity of cucumber fruits during storage at 20°C

Either parthenocarpically grown, peeled or at any stage of picking, cucumber fruits showed a tendency to increase in volume and decrease in specific gravity while they were stored under unsaturated vapour pressure at 20°C. The amount of change varied according to the treatment.Recovery from a flaccid appearance occurred in all fruit except very young ones. In those fruits the incipient recovery from wilting, an increase in volume and a decrease in specific gravity, coincided.Parthenocarpic fruits showed an increase in volume at almost the same rate in any transverse quarter of a fruit, in contrast to the pollinated ones in which the most distal quarter enlarged more than the other parts. Pithy appearance of the fruit wall was evenly distributed through a parthenocarpic fruit to a moderate degree, but at the proximal half of a pollinated one it was severe.     

Volume and specific gravity of cucumber fruits as affected by moisture condition after harvest

When cucumber fruits were stored at temperatures of 10, 20 and 30°C, in conditions that were so wet that they were able to absorb water freely through the skin, they maintained a constant specific gravity which was a hhigh as it had been at the time of picking, with a hyperbolic increase in volume. After removal to unsaturated vapour conditions at 20°C, their volume and specific gravity changed in a similar way to these of fruit which had not been in wet storage. Storage in humid conditions at 10°C resulted in almost constant specific gravity and volume, but storage at 20 or 30°C produced a gradual increase in volume as well as a decrease in specific gravity of fruits, in spite of the fresh weight showing little change. After removal of these fruits to unsaturated vapour conditions, the volume and specific gravity changed at a much faster rate with their specific rates having a peak. The shorter the humid storage, the higher the peak. The decrease in the specific gravity of picked cucumber fruits was discussed in relation to the presence of water stress.     

Phytoplankton uptake and growth rate in the Japanese egg cockle Fulvia mutica

To clarify the relationship between the quantity of food ingested by and the growth rate of the Japanese egg cockle Fulvia mutica (Reeve), we conducted a laboratory breeding experiment for 2 weeks and estimated the chlorophyll a (chl-a) concentrations in water and the increments in shell length and soft-body weight of this species under five chl-a concentrations. Moreover, we compared the relationship between cockle growth (changes in soft-body weight and shell length) and their feeding environment observed in the laboratory experiment with the results of a field investigation conducted at two sites in the Sea of Japan, Kumihama Bay (35°38′5″ N, 134°54′00″ E) and Kunda Bay (35°33′30″ N, 135°15′4″ E). The changes in soft-body weight were similar in both laboratory and field investigations, but those in shell length were not. We, therefore, considered shell length changes as unsuitable for evaluating the relationship between growth and feeding in F. mutica. Based on the changes in soft-body weight, it was possible to classify the feeding environment of this species into the following three types: (1) < 1.52 μg chl-a L−1, negative feeding environment for cockle growth; (2) 1.52–5.71 μg chl-a L−1, neutral feeding environment for cockle growth; (3) > 5.71 μg chl-a L−1, positive feeding environment for cockle growth (growth increased with increasing chl-a concentration up to about 11 μg chl-a L−1). These results indicate that maintaining chl-a concentration in the breeding water within 5.71–11 μg chl-a L−1 is desirable for rearing Japanese egg cockle.     

Quantitative estimation of the predation of marine ranched striped jack <Emphasis Type="Italic">Pseudocaranx dentex</Emphasis> by herons

The Goto station of the Japan Sea-Farming Association conducted marine ranching experiments with striped jack Pseudocaranx dentex from 1988 to 1999 in the Goto Islands, Nagasaki, Japan. Marine ranching is a stocking method where released fish are fed for some period after release in order to decrease initial mortality from starvation. Ranched fish were fed for 0, 90, and 15 days after stocking in 1997, 1998, and 1999, respectively. During the experiment, herons (grey heron Ardea cinerea, black-crowned night heron Nycticorax nycticorax, and great egret Egretta alba) were often observed preying on released fish in the ranching area. The present study estimated the number of fish preyed upon by herons during observation periods in 1997, 1998, and 1999 from the number of herons that flew into the ranching area and the predation rate on ranched fish by herons. The former was counted during sightings. The latter was estimated from the sighting observations and heron regurgitations. The number of herons that flew into the ranching area increased with the feeding period. The numbers of fish lost to predation by herons in 1997, 1998, and 1999 were estimated to be 0, 5,741, and 829, respectively.     

Rate of weight loss in proximal and distal halves of picked cucumber fruits as affected by developing seeds

In picked and stored cucumber fruits, the presence of developing seeds increased the proportion of weight loss of the proximal half compared to that of the whole fruit. This difference did not appear after pre-storage separation of the distal half, storage at 5 or 10°C, or in parthenocarpic fruits. This could not be attributed to different rates of transpiration between proximal and distal halves, but must be due to the weight displacement toward the distal region resulting from the movement of water within the fruit. Associated with the redistribution of water, developing seeds induce deteriorating fruit quality through enhancing pithiness of tissue in the proximal part, as reflected by decreasing specific gravity.     

Seagrass habitat reduces vulnerability of red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> juveniles to piscivorous fish predator

ABSTRACT:   Predation experiments were conducted in mesocosms to test the hypothesis that habitat complexity affects vulnerability of red sea bream Pagrus major juveniles to piscivorous fish predators. Juvenile behavior was video-recorded for 6 h in two structurally different habitats: vegetated with sea grass Zostera marina , and unvegetated 0.5-t tanks. Association behavior with seagrass was observed in the vegetated tank throughout the trials. Predation experiments were conducted with 30 red sea bream juveniles (29.9 mm body length) exposed to two individuals of the piscivorous fish predator Chinese sea bass Lateolabrax sp. (261.6 mm), for 6 h in 1.0-t tanks. Predation rate (no. of fish predated on per predator per h) was significantly lower in the vegetated tank (0.02/predator per h) than in the unvegetated tank (0.27/predator per h). Present experiments indicate that habitat complexity reduces vulnerability of juvenile red sea bream to predation by piscivorous fish by serving as physical and/or visual barriers and limiting the predator's ability to pursue and capture prey. Seagrass beds in the shallow coastal waters around Japan are suggested to be an important nursery for red sea bream since they provide the juveniles with habitat complexity as well as serve as a feeding ground.