Genetic population evaluation of two closely related flatfish species, the rare barfin flounder and spotted halibut, along the Japanese coast

ABSTRACT:   Barfin flounder and spotted halibut have been selected as target species for stock enhancement in Japan. Understanding the genetic condition of the wild stock is a principal requirement in any stock enhancement program. The genetic variability of barfin flounder and spotted halibut, and the population structure of spotted halibut were evaluated using microsatellite DNA markers (msDNA) and the control region of the mitocondrial DNA (mtDNA). Barfin flounder and spotted halibut showed high genetic variability at the msDNA level. Barfin flounder A was 16.7 and H _e was 0.860; spotted halibut A _n ranged from 7.7 to 10.2 and H _e ranged from 0.710 to 0.774. At the mtDNA level, high haplotype ( h  = 0.922) and low nucleotide (π = 0.002) diversities were observed for barfin flounder; however, low haplotype and nucleotide diversities ( h  = 0.603–0.620 and π = 0.001–0.002), and very low haplotype and nucleotide diversities ( h  = 0.193 and π = 0.0003) were observed for spotted halibut in the north and south locations, respectively. Slight genetic differentiation among spotted halibut sampling locations was observed from the msDNA. MtDNA analyses showed genetic differentiation between north and south locations, but not within them. The designation of north-specific and south-specific management units in the future stock enhancement activities of spotted halibut is recommended.     

Effect of methotrexate on cerebellar development in infant rats

Six-day-old rats were treated intraperitoneal injections with methotrexate 1 mg/kg, and the cerebellum was examined. Both the length and width of the vermis decreased in the methotrexate-treated group instead of the control from 4 day after treatment (DAT) onward. A significant reduction in the width of the external granular layer was detected on 2 and 3 DAT in the methotrexate group. By 4 DAT, the width of the external granular layer of the methotrexate group was indistinguishable from the control, and by 8 DAT, it was greater than that of the control. The molecular layer of methotrexate group on 8 and 15 DAT was thinner than that of the control. On 1 DAT, in the methotrexate group, there were many TUNEL and cleaved caspase-3-positive granular cells throughout the external granular layer, and they decreased time-dependently. On 1 DAT, in the methotrexate group, phospho-histone H3-positive cells in the external granular layer were fewer than in the control and tended to increase on 2–4 DAT. The p21-positive-rate of the external granule cells in the MTX group was higher than in the control on 1–4 DAT. These results suggested that methotrexate exposure on postnatal day 6 induces a delay, slowing in the migration of external granular cells to the inner granular layer, attributed to decrease or inhibition in the production of external granular cells that had arisen from apoptosis and the decrease in cell proliferative activity, resulting in cerebellar hypoplasia.     

Fiber digestion in various segments of the hindgut of horses fed grass hay or silage

We studied in vivo fiber digestibility and fermentation parameters such as volatile fatty acid concentration and in vitro degradation in each segment of hindgut of horses fed timothy hay or silage made from the same sward. Six Thoroughbred horses were fed timothy hay or silage in equal amounts (1.6% of bodyweight per day, bodyweight mean 572 kg) every 3 h per day, then slaughtered. There were no differences between hay and silage in the concentration of the total volatile fatty acids, the apparent digestibility of dry matter, organic matter, and fiber, and in vitro neutral detergent fiber (NDF) disappearance rate in each segment. The total volatile fatty acid concentration and the apparent digestibility of dry and organic matter and fiber differed ( P  < 0.01) depending on the digestive segments. Both for hay and silage, the concentration of total volatile fatty acids in the digesta liquid phase largely increased ( P  < 0.01) from the cecum to the right ventral colon, and kept a constant value from the right ventral colon to the right dorsal colon, and then decreased from the right dorsal colon to the small colon. For dry and organic matter and fiber components, the apparent digestibility changed in the same manner from former to hinder segments of the hindgut. Regardless of diet, dry and organic matter and fiber components showed lower values in the cecum and the right ventral colon and increased ( P  < 0.01) largely from the right ventral colon to the left dorsal colon, then kept constant values in segments to the rear of left dorsal colon. There were no differences in in vitro NDF disappearance among cecum, ventral colon and dorsal colon.     

Molecular phylogenetic analysis of a soil microbial community in a soybean field

We report here the phylogenetic characterization of small subunit rRNA gene sequences obtained by polymerase chain reaction (PCR) amplification of mixed population DNA extracted directly from soil in a soybean field without culturing the organisms. The phylogenetic analysis of 17 soil clones by the neighbour-joining method shows that the soil sample contained broadly diverse prokaryotes; a clone related to archaea, a clone to gram-positive bacteria with high G+C contents, two clones to green sulphur bacteria, four clones to proteobacteria, and nine clones were not in clusters of any previously reported bacterial groups, which suggests they belong to members of novel groups in Bacteria. In addition, the archaeal sequence, FIE16, is phylogenetically similar to ANTARCTIC 12, a clone obtained from surface waters of Antarctica by PCR. Their occurrence in both the ocean and soil suggests a global distribution of this archaeal group. In conclusion, rRNA gene sequences recovered from soil biomass document the occurrence of many more bacterial lingeages than have been recognized previously through cultivation-based techniques.     

Soil fabrics of the plowed layer of flooded rice fields

For a long while Japanese agricultural workers have centered their efforts to an increase in rice production, confirming the extreme importance of appropriate water controlling for a good crop. Meanwhile, Japanese farmers have traditionally practiced to keep their fields in a dry state for several days in the mid-summer. They have been convinced of healthy plants with temporarily draining off water. Its season is generally in the dog-days from the end of July to the beginning of August, and the degree of drainage seems to be decided by farmer's private views or experience. For instance, the Japan's No. 1 prize winner in technical skill of rice competition in 1950 withdrew water until light marks remained when stepped in the field, while the 1952's winner drained his field until slight cracking on ground for the period August 11 to 13 (4). They were really successful in obtaining 7.71 and 9.27 tons of brown rice per hectare, respectively. However, it appears to be needed to bring out the scientific meanings of the practice more clearly in order to make it reasonably and universaly, provided the practice is indispensable for a good rice crop.     

ABSTRACT of the Articles Printed in Journal of the Science of Soil and Manure,Japan

A contrasting occurrence of clay minerals was found within a soil profile which was derived from volcanic materials in the suburbs of Fukuoka-city, Northern Kyushu. The soil profile is located on an isolated terrace, and the morphological characteristics of the soil correspond exactly to Andosols, so-called Kuroboku soils or Humic Allophane soils.

The clay fraction of upper horizons of the soil consists largely of alumina-rich gel-like materials, gibbsite, and layer silicates such as chlorite and chloritevermiculite intergrades, while that of lower horizons is composed of allophane and gibbsite or halloysite. There was no positive indication of allophane in the upper horizons. Corresponding with the clay mineralogical composition, quartz is abundant in the fine sand fraction of the upper horizons, while the mineral is very scarce or none in the lower horizons, suggesting a close relation between the petrological nature of parent volcanic materials and the mineralogical composition of weathering products. The dominant clay mineral in the volcanic 1.10il might be dependent on the petrological nature of parent materials, and allophane is mostly formed from andesitic materials, and alumina-rich gel-like materials and layer silicates have come from quartz andesitic materials. Allophane would transform to gibbsite or halloysite according to weathering conditions, and aluminarich gel-like materials change to gibbsite under a well-drained condition.

The soil materials have been so greatly weathered that some horizons contain gibbsite of even more than 40 per cent or halloysite over 70 per cent. The morphology and mineralogy are quite similar to so-cailed “non-volcanic Kuroboku soils.”     

Influence of dispersion treatments on the properties of soil colloids

The identification and characterization of clay minerals in the soil have been carried out on the clay fraction separated from a dispersed soil suspension. The process of dispersion includes the replacement of exchangeable divalent cations with H-ions by the dilute acid treatment, the removal of organic matter with hydrogen peroxide, and the dissolution of free iron oxides with reducing and/or chelating agents.     

Grade of weathering and fertility of volcanic ash soils of Aso volcano

Texture is one of the major criterions in soil classification, probably because it has a decisive influence on soil properties. This is particularly true for volcanic ash soils. Most ashes are largely composed of sand and silt particles with little clay (11, 15). The ash weathers very rapidly (1), and clay site particles less than 2 microns in diameter occur even within a few months, as shown by Ishii at the authors' laboratory. Those clay size particles produced in the early stage of weathering are slightly weathered ones (2), and are still subject to rapid weathering, losing bases and silica under humid and well drained conditions. In consequence the clay fraction of volcanic ash soils is composed of particles which vary in degree of weathering from slightly altered glass and feldspar to true clay mineraloids and minerals. The clay fraction of younger soils as a whole is less and that of older ones is more weathered. Weathering brings a remarkable change in the properties of volcanic ash soils; for example, an inerease in soil acidity, lowering of base saturation and bulk density, or accumlation of organic matter. These changes must exert a great influence on soil fertility directly or indirectly.     

Heat of immersion of soil allophanic clays

Amorphous soil inorganic materials, specifically allophane. are believed to have a marked effect on soil properties and soil productivity, even in a relatively small amount, due to their large specific surface area, peculiar nature of surface and high chemical reactivity. They seem be present in soils, more or less, but determination of their content is generally semiquantitative or not fully reliable, because allophane includes aluminosilicates in a wide range of chemical composition and of properties, and any satisfactory, quantitative analytical method has not been established.     

Evaluation of associative effects on ruminal digestion kinetics between pasture and grains using in vitro gas production method

In vitro gas production (GP) method was used to investigate associative effects on ruminal digestion when grains (corn or barley) were supplemented to spring pasture and autumn pasture. Pasture (75%) was incubated with 25% corn or barley and gas production was monitored up to 96 h. After incubation, the residues were used to determine dry matter and organic matter digestibility (DMD and OMD). Gas production parameters were analyzed by applying a single exponential equation. Organic matter effective degradability (OMED) was determined from GP parameters and OMD. The positive associative effects on the rate of GP, DMD, OMD and OMED were observed when spring pasture was incubated with corn. However, similar effects were not observed in a barley mixture. However, for autumn pasture, both corn and barley mixtures showed positive associative effects on rate of GP, OMD and OMED. The results of this study indicated that supplementation of corn would be better than barley for spring pasture with high water‐soluble carbohydrate contents, whereas both grain supplementations were effective to obtain positive associative effects on the rate of GP and OMED for autumn pasture with high cell wall content.