Effects of epidermal growth factor (EGF) on fetal islet B cells in vitro

ABSTRACT. It has been reported that when the rat fetus is treated with streptozotocin (STZ) in vivo, islet B cells are destroyed but later recover. To investigate the process of the recovery of B cells after in vitro treatment of the fetal pancreas with STZ and the role of epidermal growth factor (EGF) in the recovery of B cells, we measured the level of insulin released from the cultured fetal pancreas and examined it histologically. As a result, we immunohistologically confirmed the regeneration of B cells in the pancreas that had been cultured for 48 hr after destruction of islet B cells by STZ treatment. An immunohistologic study using proliferating cell nuclear antigen (PCNA) showed that without the addition of EGF, the cell division index was significantly higher in the STZ-treated group (STZ group) than in the untreated group (intact group), whereas with the addition of EGF, the cell division index increased in both groups, but EGF did not have a significant cell division-promoting effect on the pancreas in the STZ group. The addition of EGF caused a significant decrease in the concentration of insulin in culture medium in both groups. These results indicate that EGF has a cell growth-promoting effect on intact fetal pancreas in vitro but has the effect of inhibiting the release of insulin, and thus suggest that EGF does not trigger the regeneration of islet B cells.     

Localization of cytokines in tendinocytes of the superficial digital flexor tendon in the horse

Although inflammatory activation of cytokines have been analyzed in various tissues, there have only been a few and as-yet-inconclusive studies on cytokines in equine tendons. In this study, the localizations of 4 cytokines (IL-1alpha, IL-1beta, TNFalpha and IFNgamma) in tendinocytes of the equine superficial digital flexor tendon (SDFT) were analyzed by the use of an immunohistochemical method. In inflamed tendons positive staining for all 4 cytokines antibodies were detected in endotedinieum cells and vascular epithelial cells. In contrast, negative or trace immunoreactions were obtained in many tendinocytes in the normal tendon. The variation in cellular immune responses depending on the kind of cytokine may reflect the physiological/pathological condition of the SDFT.     

The renal structure in an Asian elephant (Elephas maximus)

The renal structure of a female Asian elephant (Elephas maximus) was observed in both macroscopic and light microscopic levels. The left kidney was elongated-ellipse in shape, whereas the right appeared round. The left kidney was 31 cm in cranio-caudal length, 21 cm in medio-lateral length, and 2950 g in weight. The right kidney was 34 cm in cranio-caudal length, 22 cm in medio-lateral length, and 3250 g in weight. The external appearance showed the six separated renal lobes in both sides of the kidney. The four pairs of the lobes were fused in the deepest region in both sides of kidney, so we considered it as an incompletely lobated kidney in this species. We observed the proximal and distal urinary tubules in histological sections. Many renal corpuscles consisted of the glomerulus and Bowman's capsule. Many mesangial cells and some podocytes were confirmed in each glomerulus; however, Bowman's capsules were larger than those in other mammalian species.     

Comparative functional morphology of the masticatory apparatus in the long-snouted crocodiles

The masticatory muscles and their related structures of the skull were observed in the Indian gavial (Gavialis gangeticus), the false gavial (Tomistoma schlegelii), and the African slender-snouted crocodile (Mecistops cataphractus) to detail some morphological differences in comparison with the other crocodile species, and to compare and elucidate the functional strategy of themasticatory apparatus in these long-snouted species. The Musculus pterygoideus posterior was relatively smaller in the three species compared with many short-snouted crocodiles. It suggests that the masticatory power in fish-eating long-snouted species is not so high as in the short-snouted crocodiles, while the masticatory muscles were morphologically different among the three long-snouted species as follows. The M. pterygoideus posterior of the false gavial was extended in the lateral side of the lower jaw unlike the Indian gavial. The M. pseudotemporalis and the Fenestra supratemporalis were largely developed in the Indian gavial, however we suggest that the other two species possess the weak bundles in this muscle. The false gavial and the African slender-snouted crocodile have the pterygoid bone well-developed extending dorso-ventrally and it is suggested that the M. adductor mandibulae posterior attached to the pterygoid bone may be much larger than the Indian gavial. These data morphologically clarify the masticatory mechanism in the long-snouted crocodiles different from the short-snouted species, and demonstrate that the evolutional strategy to share the functional role in the masticatory muscles have been differently established between the Indian gavial and the other two species. We also obtained the morphological data in the fossil skull of the Machikane crocodile (Toyotamaphymeia machikanense) and concluded from the fossil characters that the considerable developments of the M.pterygoideus posterior and the M.pseudotemporalis in this species had not morphologically been consistent with both the Indian and false gavials.     

Influence of antibiotics used as feed additives on the immune effect of erysipelas live vaccine in swine

To investigate the influence of antibiotics used as feed additives on the immune response to erysipelas live vaccine, the pig inoculation test was applied. Avilamycin, oxytetracycline quaternary salt, enramycin, virginiamycin and tylosin phosphate were selected as test antibiotics. Five experimental feeds containing each antibiotic at the highest concentration permitted for feed additives in Japan, and the basal diet lacking antibiotics were examined. Twenty-nine pigs were divided into six groups. At first all the groups were fed with the antibiotic-free basal diet for 7 days, and then each group received the experimental feeds. On the 14th day after feeding with test feeds all the pigs, except for one control pig in each group, were immunized with the vaccine and all the pigs were then challenge-exposed to a virulent strain of Erysipelothrix rhusiopathiae 14 days after vaccination. The clinical response was observed every day for 14 days. In all the groups, most of the vaccinated pigs did not develop any clinical signs of acute erysipelas after the challenge exposure, whereas non-vaccinated control pigs died or showed severe generalized erythema with profound depression and anorexia. No differences in the protection against the challenge exposure were observed among the groups. Therefore, the present results suggest that these selected antibiotics would not interfere with the immune effect of the vaccine if given at the usual concentrations used for feed additives.     

An epidemiological survey of Chrysanthemum chlorotic mottle viroid in Akita Prefecture as a model region in Japan

In epidemiological surveys on Chrysanthemum chlorotic mottle viroid (CChMVd) in various chrysanthemums cultivated in Akita Prefecture, Japan, in 2002–2005, approximately 20% of cultivars harbored CChMVd, including more symptomatic types than nonsymptomatic. Large-flowered cultivars were less frequently infected than small-flowered and spray types. The number of CChMVd-infected chrysanthemums is increasing, and the disease is found throughout major chrysanthemum-producing districts. Chrysanthemums infected only with CChMVd, in general, had no noticeable symptoms of disease. Most of those dually infected with known viruses and/or viroid also had no symptoms characteristic of chlorotic mottle disease. The lack of noticeable symptoms in major Japanese cultivars may have resulted in the unnoticed spread of the viroid.     

Ineffectiveness of pruning to control citrus huanglongbing caused by <Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter americanus

The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation) would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old ‘Valência’, ‘Hamlin’ or ‘Pêra’ sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age, variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before pruning the lower the percentage of trees that remained asymptomatic after pruning.     

Developmental changes in pituitary–thyroid axis, and formation of gonads in leptocephali and glass eels of Anguilla spp.

SUMMARY: Pituitary, thyroid gland and gonads in leptocephali of Japanese eel Anguilla japonica (19.8–32.6 mm in total length), A. obscura (45.0 mm), and A. bicolor pacifica (49.5 mm) and those in glass eels of the Japanese eel were histologically and immunohistochemically examined in order to observe the developmental changes of these endocrine organs in the Anguillidae. The pituitary, consisting of adenohypophysis and neurohypophysis in Japanese eel leptocephali over 22.5 mm, did not contain thyroid stimulating hormone (TSH) immunoreactive cells. Such cells were, however, detectable in the more developed pituitaries of leptocephali of A. obscura and A. bicolor pacifica and in those of glass eels. Conversely, thyroxine (T₄)-immunoreactive thyroid follicles could be detected in all specimens, both leptocephalic and glass eel. Only in glass eels, gonads were found in the body cavity, and these gonads harbored one or two primordial germ cells (PGC) per cross-section. Our results indicate that thyroid hormones (TH) production started prior to TSH production, and that TSH and TH are both secreted during the metamorphosis from leptocephalus to glass eel. Therefore, it is plausible that the TSH–TH axis is involved in the metamorphosis from leptocephalus to glass eel, but not in the early growth from preleptocephalus to leptocephalus.     

Mycoplasma iowae species-specific DNA probe

A Mycoplasma iowae (MI) species-specific DNA probe (designated pMI-2) of 6.0 kbp (kilobase pairs) was isolated from an MI strain I-695 genomic library prepared in plasmid pUC8 and Escherichia coli strain JM83. When labeled with [32]P by nick translation, the probe hybridized in dot blot assays with 6 reference strains and 8 field isolates of MI but not with 16 other known species of avian mycoplasmas. The pMI-2 probe detected a minimum of 1.5 ng of MI strain I-695 chromosomal DNA. Under identical conditions of hybridization, the probe did not hybridize with a high concentration (200 ng) of M. gallisepticum or M. synoviae chromosomal DNA.