The effects of selective logging on stand structure and the regeneration of subboreal forests in Hokkaido, northern Japan

We investigated the effects of selective logging on stand structure and regeneration in selectively logged subboreal forests in Taisetsuzan National Park in Hokkaido in northern Japan. The basal area decreased and the size structure of trees altered in the stands studied due to repeated, intense selective logging, in which larger trees were cut down as a priority. Sapling density in the stands was much lower than that in primary forests. In the simple and multiple regression analyses that were used to estimate the effects of selective logging on sapling density, sapling density had a significant positive correlation with tree density and had little correlation with the density of logged stumps or the height ofSasa (dwarf bamboo) growing on the forest floor. These results suggest that the establishment sites around canopy trees influenced the establishment of saplings, rather than the gaps caused by selective logging. However, both the coefficient of determination and the standardized partial regression coefficient of multiple regression analysis were higher for the stand with a dense cover ofSasa than for the stand with a sparse cover ofSasa. Thus, the success of regenerating forests with selective logging depends on both the site of advanced regeneration and the light conditions that regulate growth.     

Pathogenicity for mice and swine of Erysipelothrix isolates from the tonsils of healthy cattle

The pathogenicity of 79 Erysipelothrix isolates from bovine tonsils for mice and swine was determined. Five (6.3%) isolates were lethal for mice. These isolates belonged to serovars 1b (one isolate), 2 (2), 19 (1) and 21 (1). The 50% lethal dose values of the isolates ranged from 0.33 to 5x10(2) CFUs in mice. Twenty Erysipelothrix isolates (25.3%) were weakly virulent inducing only emaciation while 12 (15.2%) inducing emaciation and ruffled hair. In swine, clinical signs of varying severity were observed. Four isolates were virulent, capable of inducing localized or generalized urticarial lesions accompanied with a rise in body temperature after intradermal inoculation. One isolate each of serovars 1b, 2 and 19 was highly virulent, capable of inducing generalized urticarial lesions while another Erysipelothrix isolate of serovar 2 induced only a localized urticarial lesion at the site of inoculation. Another isolate of serovar 1b induced itching and irritation without obvious urticarial lesion at the site of inoculation. On the other hand, one isolate of serovar 21 and two other isolates of serovar 2 could not induce experimentally any clinical sign of erysipelas other than rise in body temperature. There was a rise in growth agglutination (GA) titer of serum in all the inoculated swine. These observations suggest that Erysipelothrix isolates from cattle are pathogenic for mouse and swine, and may also be pathogenic for other animals and humans.     

Identification of tumor-initiating cells in a canine hepatocellular carcinoma cell line

Tumor-initiating cells (TICs) or cancer stem cells (CSCs), a small subset of tumor cells, are involved in tumor initiation, progression, recurrence and metastasis. In human hepatocellular carcinoma (HCC), TICs are enriched with cell surface markers and have the ability to self-renew and differentiate tumors at a high frequency. We established a canine HCC cell line, HCC930599, and analyzed it for stem and progenitor cell marker expression using flow cytometry. HCC930599 showed high CD44 and CD29, moderate CD90, and low CD133, CD34, CD24, CD117, and CD13 expression. CD90⁺CD44⁺ and CD90⁻CD44⁺ cells were characterized using the in vitro sphere assay and an in vivo transplant model. CD90⁺CD44⁺ cells acquired enhanced self-renewal capacity, proliferative activity and tumourigenicity compared with CD90⁻CD44⁺ cells, suggesting that TICs exist in the HCC930599 cell line and that CD90 is a marker for enriched TICs. Understanding TIC characteristics may help elucidate hepatic carcinogenesis and HCC therapy development.     

Use of epichlorohydrin-treated chitosan resin as an adsorbent to isolate kappa-casein glycomacropeptide from sweet whey

This study was undertaken to develop a method to isolate glycomacropeptide (GMP), a bioactive compound, from sweet whey by using chitosan resins as anion exchangers. Shrimp shells were used to prepare two chitosan (polyglucosamine) resins, one with the primary amine (-NH(2)) (resin A) and the other with the secondary amine (-NH-) (resin B) as the major functional group. These resins were tested as adsorbents for the isolation of GMP from sweet whey, and the results obtained were compared with those obtained with commercial anion exchangers. The most important finding in this experiment was that the GMP binding capacity of resin A was much higher than that of resin B. Resin A may be the anion exchanger to be tested for industrial scale production of GMP. Amino acid analysis of the GMP-depleted whey fraction suggests that this product can replace sweet whey as an ingredient in various food products including infant formulas, bakery products, and beverages.