Estimation of transport distance of fine particulate organic matter in relation to channel morphology in tailwaters of the Lake Biwa and reservoir dams

Knowledge on transport and deposition of fine particulate organic matter (FPOM) from reservoir dams is increasingly required for habitat management and restoration of dam tailwater ecosystems. Variations in the transport distance of FPOM, however, have never been studied well, particularly in relation to channel morphology, due to channel size restrictions of artificial tracers such as corn pollen when applied to larger river channels. This study aims to show the relations between FPOM retention efficiency and channel morphology in dam tailwaters using lentic plankters as tracers. We estimated the mean transport distance, S _p, by calculating downstream reduction ratios of lentic tracer plankters and calculated the deposition velocity, v _dep. Suspended FPOM samples were collected in tailwaters of two river channels below reservoir dams and two artificial canals below Lake Biwa in the Yodo River system. The longest S _p (19.2 km) and the shortest one (2.2 km) were recorded in the deep canal and shallow canal, respectively, showing a positive correlation with channel hydraulic radius. The values of v _dep were 4.7–6.4 times higher in river channels than in artificial canals. These results indicate that increasing complexity of bed morphology can minimize S _p, whereas bed degradation and armored bed materials may lead to increased S _p. Advantages of lentic plankters as tracers for estimating distance ranges of reservoir dam impact on river ecosystems are also discussed.     

Effect of temperature on the velocity of erythrocyte aggregation

The velocity of the aggregation of human erythrocytes was examined in the range of 5-43 degrees C with a rheoscope combined with a video camera, an image analyzer and a computer. (1) With increasing temperature, the velocity of erythrocyte aggregation induced by fibrinogen, immunoglobulin G and artificial macromolecules (dextran of 70 kDa and poly(glutamic acid) of 50 kDa) increased. However, the relationship between the velocity of erythrocyte aggregation and the temperature was different among these macromolecules. (2) In 70% autologous plasma, the velocity of erythrocyte aggregation was minimum at 15-18 degrees C, and increased at both higher and lower temperatures. (3) The shape of erythrocyte aggregates in 12 mumol/l fibrinogen (containing 770 mumol/l albumin) and in 70% autologous plasma was dependent on temperature: three-dimensional below 15-18 degrees C and one-dimensional (mainly rouleaux) above 15-18 degrees C. However, the shape of aggregates in 27 mumol/l immunoglobulin G (containing 770 mumol/l albumin) was three-dimensional in all temperature ranges. (4) The temperature dependency of erythrocyte aggregation was discussed in terms of the changes of medium viscosity, of erythrocyte properties and of bridging macromolecules.     

Mapping and disruption of the cybB gene coding for cytochrome b561 in Escherichia coli

Abstract The cybB gene on a plasmid encoding cytochrome b ₅₆₁ in Escherichia coli was disrupted by insertion of Km^rl determinant DNA. The cromosomal cybB gene was replaced by the inactivated cybB gene on the plasmid by homologous recombination using λ phage lysogenization and heat-induction. The replacement was confirmed by Southern and Western blotting analyses. Deficiency on the cybB gene product did not affect the growth properties of the cells, and the oxidase activities of the cells dependent on various substrates were similar to those of the parental strain. Cytochrome b ₅₆₁ is concluded to be expressed in E. coli , but may not play a major role in cell growth. In the genetic map of E. coli , the cybB gene was determined by conjugational and transductional crosses to be at 31 min between trg and terC .     

Analysis of bacterial populations in a grassland soil according to rates of development on solid media

Abstract The process of colony formation by bacteria from grassland soil sampled in April, July and September was simulated by a colony-forming curve (CFC). The CFC was a super-imposition of several component curves (cCFC) given theoretically by the first order reaction (FOR) model [3,6]. The pattern of FOR model curves was not influenced by the time of sampling and four cCFCs were always recognized during an incubation period of 160 h. It was considered that the CFC describes an inherent property of the bacterial population of the field. Bacterial isolates were obtained from colonies produced in each of four cCFCs on agar plates. Isolates corresponding to one cCFC were classified as one group. The bacterial isolates were characterized by morphological and physiological tests and subsequently clustered. Few oligotrophic bacteria were obtained among bacteria which produced visible colonies within 63 h of incubation time. On the other hand, approx. 50% of bacteria which produced v colonies after 63 h were oligotrophic bacteria. The time required for the appearance of the first colony, t _r of the FOR model, was very similar in the isolates belonging to one group. A close linear relationship was observed between t _r value and doubling time of isolates.     

Morphology,physics, chemistry and biology of Lake Rara in West Nepal

A survey of oligotrophic Lake Rara, the biggest lake in Nepal, was carried out from 1982 till 1984. Mean depth is 100 m, and maximum depth is 167 m. The surface area covers 9.8 km², and the lake contains 0.98 km³ volume of water. Transparency was about 16 m, photoquantum yield decreased exponentially with depth below 5 m, and the extinction coefficient was 8.3 × 10⁻². The concentration of Chl.-a was in the range of 0.06–0.46 mg m⁻³, and total nitrogen was 18–30 μg 1⁻¹. The whole water column was well oxygenated. Primary productivity was extremely low. It has more than 30 inflowing brooks and one outlet. The water quality of the brooks changes drastically with their location. The pH, electrical conductivity, and EDTA hardness in the waters from a landslide area were high. In the waters from a rich pine forest they were extremely low. The zooplankton consisted of two species of protozoa, five species of rotifers, two species of Cladocera, and two species of Copepoda. The zooplankton density range was 6200–16200 individuals m⁻³. The minimum was on November 11th, 1983 and the maximum on August 19th, 1983.     

The Escherichia coli cytochrome b556 gene, cybA, is assignable as sdhC in the succinate dehydrogenase gene cluster

Abstract The cytochrome b556 -deficient mutant Escherichia coli K12 strain TK3D11 [7] could not grow with succinate as the sole carbon source, but could grow well on dl -lactate. This finding suggested that cytochrome b556 is primarily responsible for oxidative metabolism and utilization of succinate. 24 Amino acid residues at the amino-terminal of purified cytochrome b556 were determined. This sequence coincided completely with amino acid residues 4 to 27, predicted from the DNA sequence of the sdhC gene, one of the unassigned open reading frames of the sdh gene cluster recently reported by Wood et al. [16]. Based on these and other results, we concluded that cybA , the gene for cytochrome b556 , is assignable as sdhC .     

Isolation of virus causing hemorrhagic fever with renal syndrome (HFRS) through a cell culture system

Twenty-three rat lung specimens collected in outbreaks of hemorrhagic fever with renal syndrome (HFRS) in three medical institutions were inoculated onto the VERO-E6 cell monolayers. After several blind passages, an agent growing serially in the cell cultures and reacting specifically with known HFRS-positive sera was isolated from two of these specimens. The two isolates were antigenically identical each other. The agent, named strain SR-11, was identified as the causative virus of HFRS by its antigenic identity with E6 cell-adapted HFRS virus, Hantaan 76-118 strain, and the specific reactions with sera from various HFRS cases.     

Ferredoxins in Developing Spinach Cotyledons: The Presence of Two Molecular Species

An antibody for ferredoxin was used to investigate the developmentof ferredoxin during the greening of spinach cotyledons. Ferredoxinwas present in 8-day-old etiolated cotyledons and increasedwith illumination, which means that the synthesis of ferredoxinwas both light dependent and independent. The ferredoxin purified from etiolated cotyledons, greeningcotyledons, and mature leaves was a mixture of two chemicallydistinct molecular species; ferredoxin I and II. The relativecontents of these two species varied with the stage of developmentand the conditions used. Ferredoxin I was identical with that isolated previously asvalidated by its amino acid sequence [Matsubara and Sasaki (1968)J. Biol. Chem. 243: 1732]. The complete amino acid sequenceof the second component, ferredoxin II, was determined as well.It was composed of 97 amino acid residues and differed fromferredoxin I by 25 residues. (Received October 16, 1982; Accepted December 14, 1982)