A releaser pheromone that attracts methyltestosterone- treated immature fish in the urine of ovulated female rainbow trout

SUMMARY: Behavioral experiments concerning a releaser pheromone in the urine of female rainbow trout were performed using immature fish administered orally with 17α-methyltestosterone (MT) during the non-spawning season. The urine was collected by catheter. The frequency of entries of test fish was recorded in each channel scented by test and control solutions in a Y-maze trough. The behavior of both MT-treated and control fish demonstrated that they could not discriminate the differences between distilled and environmental water as control solutions. There was also no difference between MT-treated and control fish when distilled and environmental water were introduced. The MT-treated immature fish were attracted to the channel scented by ovulated female urine. Neither coelomic fluid nor the immature female urine had any effect on the behavioral responses of MT-treated fish, while immature control fish had no preference for the urine of ovulated females. These results suggest in rainbow trout that ovulated female urine contains a releaser pheromone to attract mature males, and that androgens are involved in the sensory mechanisms detecting the releaser pheromone in fish.     

Apocrine adenocarcinoma in a golden hamster.

An apocrine adenocarcinoma was observed in the subcutis of the abdomen of golden hamster. Histologically, the tumor cells irregularly formed multiple layers of cysts and some detached cells were presented in the cystic space. PAS stain with alpha-amylase digestion revealed PAS-positive alpha-amylase-resistant granules in the cytoplasm. Immunohistochemically, cytokeratin was demonstrated in the tumor cells. By electron microscopy, the tumor cells had an oval nucleus with invagination, abundant cytoplasmic organelles and microvilli protruding into the intercellular spaces.     

Mycobacterium avium infection through the alimentary tract in mice

Intestinal infection by Mycobacterium avium was investigated in C57BL/6 and BALB/c mouse strains. Single intragastric administration of a massive dose (10(8] or multiple administration of a lower dose (10(7), 10 times) established infection principally in the mesenteric lymph-node (MLN); a continuous or intermittent fecal excretion of the bacilli was detected by 6-8 weeks after the administration. Based on three criteria--isolation of the organisms from the MLN and from feces, and detection of acid-fast bacilli in sections of the MLN--germ-free (GF) BALB/c mice exhibited clearer dose-effect relations than the flora-bearing (FB) counterparts. After intragastric administration, the organisms were probably trapped in the Peyer's patch and then transferred to the MLN at an early period (by 4-7 days), persistent infection thus being established in the MLN. Systemic involvement evolved both in athymic and euthymic mice after a prolonged period of time (more than 40 weeks) showing far more severe involvement in the former regardless of the presence of floral organisms.     

Catalog of Micro-Tom tomato responses to common fungal, bacterial, and viral pathogens

Lycopersicon esculentum cultivar Micro-Tom is a miniature tomato with many advantages for studies of the molecular biology and physiology of plants. To evaluate the suitability of Micro-Tom as a host plant for the study of pathogenesis, Micro-Tom plants were inoculated with 16 well-known fungal, bacterial, and viral pathogens of tomato. Athelia rolfsii, Botryotinia fuckeliana, Oidium sp., Phytophthora infestans, and Sclerotinia sclerotiorum caused typical symptoms and sporulated abundantly on Micro-Tom. Micro-Tom was resistant to Alternaria alternata, Corynespora cassiicola, and Fusarium oxysporum. When Micro-Tom was inoculated with 17 isolates of Ralstonia solanacearum, many isolates induced wilt symptoms. Agrobacterium tumefaciens also was pathogenic, causing crown galls on stem tissue after needle prick inoculation. In Micro-Tom sprayed with Pseudomonas syringae pv. tomato, P. s. pv. tabaci, or P. s. pv. glycinea, bacterial populations did not increase, and yellow lesions appeared only on leaves sprayed with P. s. pv. tomato. Tomato mosaic virus, Tomato aspermy virus, and Cucumber mosaic virus systemically infected Micro-Tom, which developed symptoms characteristic of other cultivars of tomato after infection with the respective virus. These results indicated that Micro-Tom was generally susceptible to most of the important tomato pathogens and developed typical symptoms, whereas certain pathogens were restricted by either hypersensitive resistance or nonhost resistance on Micro-Tom. Therefore, an assortment of Micro-Tom–pathogen systems should provide excellent models for studying the mechanism of susceptible and resistant interactions between plants and pathogens.     

Physiological Races and Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae Isolated from Crisphead Lettuce in Japan

One hundred and sixteen isolates of Fusarium oxysporum f. sp. lactucae obtained from 85 fields in three crisphead lettuce-producing areas in Nagano Prefecture, Japan were typed for races using differential cultivars Patriot, Banchu Red Fire and Costa Rica No. 4. They were also grouped into vegetative compatibility groups (VCGs) using complementation tests with nitrate non-utilizing (nit) mutants. Two California strains reported as F. oxysporum f. sp. lactucum, a type culture of F. oxysporum f. sp. lactucae, and 28 avirulent isolates of F. oxysporum obtained from crisphead lettuce were included for comparison. Among Nagano isolates, 66 isolates were identified as race 1, and 50 as race 2. Race 1 strains derived from Shiojiri and Komoro cities and race 2 from Kawakami village and Komoro city. All isolates of race 2 were biotin auxotrophs, and the race could be distinguished based on its requirement for biotin on minimal nitrate agar medium (MM). Pathogenic isolates were classified into two VCGs and three heterokaryon self-incompatible isolates. Strong correlations were found between race and VCG. All the race 1 strains were assigned to VCG 1 except self-incompatible isolates, and all the race 2 strains to VCG 2. The 28 avirulent isolates of F. oxysporum were incompatible with VCG 1 and VCG 2. California strains was vegetatively compatible with VCG 1, and they were assigned to race 1. Based on vegetative compatibility, these two races of F. oxysporum f. sp. lactucae may be genetically distinct, and F. oxysporum f. sp. lactucae race 1 is identical to F. oxysporum f. sp. lactucum. Received 7 May 2002/ Accepted in revised form 6 September 2002     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

The functional-morphological adaptive strategy of digestive organs of decapodiform cephalopods

The digestive organs in decapodiform cephalopod species morphologically vary by individual lifestyle. We examined the following six species of adult decapodiformes cephalopods representing different habitats: Todarodes pacificus, Loligo bleekeri, Loligo edulis, Watasenia scintillans (pelagic), Sepia lycidas and Euprymna morsei (benthic). L. bleekeri and L. edulis possess a bursiform cecal sac connected to the cecum. Pelagic species have a single digestive gland smaller than in benthic species. T. pacificus has an oval digestive gland larger than that of L. bleekeri and L. edulis, which possess withered-looking and smaller digestive glands. In contrast, the digestive glands in benthic species are paired. S. lycidas and E. morsei have well-developed and larger digestive glands than those of the pelagic species. Well-developed digestive duct appendages are found in benthic species. In qualification of the mass of digestive organs, pelagic species have smaller stomachs, digestive glands and digestive ducts’ appendages than benthic species. Because pelagic species need to swim, they may possess smaller stomachs and larger cecums for more rapid digestion. A smaller digestive gland may have the advantage of reducing the body weight in pelagic species for rapid swimming. In contrast, since benthic species require a longer time for digestion than pelagic species, they compact more food in their stomachs and absorb nutrients via more organs, such as the digestive grand and digestive duct appendages, in addition to cecum.     

Mesh-like vascular changes in copper deficiency-induced rat cardiomyopathy

The pathological effects of copper deficiency (COD) are well known. However, the pathogenesis of cardiomyopathy resulting from COD remains unclear. In this study, aimed to elucidate the pathogenesis of COD-induced cardiomyopathy by examining the morphology of the cardiovascular system in copper-deficient rats using histopathology, immunohistochemistry, and scanning and transmission electron microscopy. Changes detected in the myocardium and interstitium were consistent with those reported for COD. Morphological changes included mesh-like changes in the capillary endothelial cells that appear to be a novel finding in COD-induced cardiomyopathy. These changes are hypothesized to result from abnormal vascular remodeling following damage to the basement membrane and due to the mechanical effects of myocardial contractions. Although cardiomyopathy may be associated with microcirculatory disorders arising from these lesions, further investigations are necessary to demonstrate a causal relationship between the pathogenesis of cardiomyopathy and the contribution of these lesions to disease progression.     

A morphological analysis of the skull size and shape of Kerivoulinae (Chiroptera: Vespertilionidae) from Vietnam

Southeast Asia is a region of high biodiversity, containing species of plants and animals that are yet to be discovered. In this region, bats of the subfamily Kerivoulinae are widespread and diverse with six species recorded in Vietnam. However, the taxonomy of the Kerivoulinae in Asia is complicated. In our study, we used diagnostic characters and multivariate analysis to determine morphological differences between the genera Kerivoula and Phoniscus. We showed that the two genera are distinguishable by the size of second upper incisors, the shape of skull, nasal sinus, canines, second upper and lower premolars. In addition, the two genera can be osteometrically separated by measurements of the braincase height, interorbital width and shape of anterior palatal emargination. Our data clearly revealed the morphological variations in the skull shape of Kerivoula hardwickii in Vietnam. This suggests a possible separation into three morphotypes, representing cryptic species supported by statistical differences with wide variation in skull shape, size and teeth. These results demonstrated Kerivoula hardwickii can be separated three subspecies, and the result will serve as the basis for the future assessment and classification of this group in Southeast Asia.     

Hemorrhagic necrotizing splenitis in a slaughter pig infected with Arcanobacterium species

A 6-month-old barrow presented with lethargy, inappetence and dysstasia. At necropsy, multiple coalescing hemorrhagic foci were detected in the margins of the spleen. Gram-positive bacilli were isolated from the spleen, kidney, muscle and liver. Comparative 16S rDNA gene sequencing analysis of the isolates (TO16177) revealed that they would be the same species of unpublished Arcanobacterium species strain HJ57-14E (accession no. gi 18873551) (99.7% similarity based on a comparison of 675 bp). Histologic examination of the splenic tissue sections revealed extensive necrosis and inflammation, and gram-positive bacilli were discernible. Multifocal necrosis was also detected in the liver. Immunohistochemically, the isolates were cross-reacted with polyclonal antibodies against Arcanobacterium pyogenes and Actinomyces naeslundii, and the reaction was strong for the latter. Similar reactions were found in the suppurative lesions of the tonsil, and occasionally in the spleen and lymph nodes. The present results indicate that the unpublished Arcanobacterium species induced multiple organ failure accompanied by acute hemorrhagic necrotizing splenitis in this growing-finishing pig.