Experimental gizzard erosions in specific-pathogen-free chicks by serotype 1 group I avian adenoviruses from broilers

The pathogenicity of serotype 1 group I avian adenovirus (GIAAV) strains isolated from gizzard erosions for 1-wk-old specific-pathogen-free (SPF) chickens was investigated. In Experiment 1, SPF chickens inoculated orally with a serotype 1 strain (Tokushima2000/GE) of GIAAV isolated from gizzard erosion in broilers were euthanatized and necropsied from 3 to 12 days after inoculation. Clinically, there were no significant signs in the chickens inoculated with Tokushima strain. The gizzards were found macroscopically to be dilated with liquefied contents. The koilin layer of the gizzard exhibited multifocal white lesions with occasional erosions. Gross lesions of the koilin layer (white foci and erosion) appeared at 3 days after inoculation and persisted until 12 days after inoculation. The gross lesions were most severe at 9 days after inoculation. Histologically, multifocal degeneration, necrosis, and loss of the glandular epithelial cells with intranuclear inclusions, liquefactive change of koilin substance, and erosive lesions of koilin layers and surface epithelium of the gizzards were observed. Macrophages increased in the focal areas of the lamina propriabelow the liquefactive koilin substances. Immunohistochemically, intranudear inclusions were positive against GIAAV antigen. Histologic lesions of gizzards were most severe at 7 and 9 days after inoculation, but the frequency of intranuclear inclusions was greatest at 5 days after inoculation. In Experiment 2, the pathogenicities of four strains of serotype 1 GIAAV for 1-wk-old SPF chickens were compared. Three strains isolated from gizzard erosion had similar pathogenicities but one strain from a normal chicken was not pathogenic for chickens. These results suggest that gizzard erosions by serotype 1 GIAAV infection may occur in broiler chickens in Japan.     

A Point Mutation in the Two-Component Histidine Kinase BcOS-1 Gene Confers Dicarboximide Resistance in Field Isolates of Botrytis cinerea

ABSTRACT Partial DNA fragments of Botrytis cinerea field isolates encoding the putative osmosensor histidine kinase gene (BcOS1) were cloned by polymerase chain reaction amplification and the predicted amino acid sequences were compared between dicarboximide-sensitive and resistant field isolates. The predicted BcOS1p is highly homologous to osmosensor histidine kinase OS1p from Neurospora crassa including the N-terminal six tandem repeats of approximately 90 amino acids. Four dicarboximide-resistant isolates of B. cinerea (Bc-19, Bc-45, Bc-682, and Bc-RKR) contained a single base pair mutation in their BcOS1 gene that resulted in an amino acid substitution in the predicted protein. In these resistant isolates, codon 86 of the second repeat, which encodes an isoleucine residue in sensitive strains, was converted to a codon for serine. The mutation of Botrytis field resistant isolates was located on the second unit of tandem amino acid repeats of BcOS1p, whereas the point mutations of the fifth repeat of OS1p confer resistance to both dicarboximides and phenylpyrroles and also osmotic sensitivity in Neurospora crassa. These results suggest that an amino acid substitution within the second repeat of BcOS1p is responsible for phenotypes of field resistant isolates (resistant to dicarboximides but sensitive to phenylpyrroles, and normal osmotic sensitivity) in B. cinerea.     

Leydig cell hyperplasia in an ENU-induced mutant mouse with germ cell depletion

Repro22 is an N-ethyl-N-nitrosourea (ENU)-induced mutation in mice showing depletion of both male and female germ cells. In the present study, we investigated the male phenotypes of the mutant mouse at the adult stage. The repro22/repro22 homozygous mice showed reduced body weights as well as markedly reduced testis weights. Histological examination of the testes at 4 and 10 months of age showed no germ cells in the seminiferous tubules of the affected testis while a number of Sertoli cells were observed in the tubules. In addition to the germ cell depletion, the testes of the affected mouse contained expanded intertubular spaces that were filled by Leydig cell-like interstitial cells. These interstitial cells were confirmed to be Leydig cells by immunohistochmical staining using anti-3beta-HSD antibody. The estimated number of Leydig cells in the affected testes at 10 months of age increased approximately 2 fold compared with those of normal testes. Furthermore, the plasma testosterone levels of the affected mice at 10 months of age were significantly higher than those of the normal mice. These findings indicated that the repro22/repro22 mouse developed hyperplasia of Leydig cells that was presumably caused by the absence of germ cells in the seminiferous tubules.     

Artificial insemination with canine spermatozoa frozen in a skim milk/glucose-based extender

Due to the recent outbreak of avian influenza, transportation of frozen canine semen with egg yolk has been sharply restricted. Thus, there is urgent need to develop a novel egg yolk-free extender for freezing canine spermatozoa. In the present study, the effect of using skim milk/glucose (SG)-based extender without egg yolk on the motility and fertilizing capacity of canine spermatozoa frozen-thawed in the presence of glycerol was examined. There was a tendency for the proportion of motile spermatozoa exposed to SG-based extender for 3 h to be higher than that exposed for 1 h, but the difference was not significant. The motility and other viability parameters of canine spermatozoa after thawing were similar to those obtained with an egg yolk-based extender. When spermatozoa frozen with SG-based extender containing glycerol after 3 h exposure were transcervically inseminated into 2 recipient bitches, a total of 6 pups were obtained. These results suggest that a simple extender composed of skim milk, glucose and glycerol is useful for cryopreservation of canine spermatozoa, which may contribute to improved exchange of genetic material and efficient production of companion and working dogs, such as guide dogs for the blind.     

Congenital cutaneous fibropapillomatosis without evidences of papillomavirus infection in a Holstein-Friesian calf

A male Holstein-Friesian calf was born with multiple, cauliflower-like, pale pink cutaneous masses on the head and limbs. On histopathological examination, the cutaneous masses were diagnosed as congenital cutaneous fibropapillomatosis. Those lesions involved focal proliferation of sebaceous gland in the dermis. There were no histological findings to suggest bovine papillomavirus infection, such as the presence of intranuclear inclusion bodies, large keratohyalin granules, and koilocytosis. Furthermore, papillomaviral antigens and DNA were not detected by immunohistochemistry and polymerase chain reaction, respectively. These results suggested that there was no association between these cutaneous lesions and bovine papillomavirus infection, and the lesions were considered as harmartomatous changes.     

Regulation of biosynthesis,perception, and functions of strigolactones for promoting arbuscular mycorrhizal symbiosis and managing root parasitic weeds

Strigolactones (SLs) are carotenoid‐derived plant secondary metabolites that play important roles in various aspects of plant growth and development as plant hormones, and in rhizosphere communications with symbiotic microbes and also root parasitic weeds. Therefore, sophisticated regulation of the biosynthesis, perception and functions of SLs is expected to promote symbiosis of beneficial microbes including arbuscular mycorrhizal (AM) fungi and also to retard parasitism by devastating root parasitic weeds. We have developed SL mimics with different skeletons, SL biosynthesis inhibitors acting at different biosynthetic steps, SL perception inhibitors that covalently bind to the SL receptor D14, and SL function inhibitors that bind to the serine residue at the catalytic site. In greenhouse pot tests, TIS108, an azole‐type SL biosynthesis inhibitor effectively reduced numbers of attached root parasites Orobanche minor and Striga hermonthica without affecting their host plants; tomato and rice, respectively. AM colonization resulted in weak but distinctly enhanced plant resistance to pathogens. SL mimics can be used to promote AM symbiosis and to reduce the application rate of systemic‐acquired resistance inducers which are generally phytotoxic to horticultural crops. © 2019 Society of Chemical Industry     

Comparative QTL mapping for male sterility of cultivated strawberry (Fragaria × ananassa Duch.) using different reference genome sequences

Male sterility is one of the reproductive isolation systems in plants and quite useful for F₁ seed production. We previously identified three independent quantitative trait loci (QTLs) for male sterility of cultivated strawberry, Here, we identified the specific subgenomes in which these QTLs are located by QTL-seq approach. QTLs qMS4.1, qMS4.2, and qMS4.3 were mapped separately in subgenomes Fvb4-4, Fvb4-3, and Fvb4-1, respectively, in ‘Camarosa’ genome assembly v. 1.0.a1. Candidate regions of qMS4.1 and qMS4.3 were clearly detected around 12–26 Mb in Fvb4-4 and 12–14 Mb in Fvb4-1, respectively; those of qMS4.2 were fragmented in Fvb4-3, which suggests that some scaffolds were incorrectly assembled in Fvb4-3. qMS4.3 was mapped to chr4X1 of ‘Reikou’ genome assembly r2.3, and qMS4.1 and qMS4.2 were both mapped to chr4Av, which indicates that differentiation of the subgenomes in which both QTLs are located was insufficient in ‘Reikou’ r2.3. Although ‘Camarosa’ genome assembly v. 1.0.a1 is an unphased map, which merges homologous chromosomes into one sequence, ‘Reikou’ genome assembly r2.3 is a phased map, which separates homologous chromosomes. QTL mapping to different reference genomes clearly showed the specific features of each reference genome, and that using different kinds of reference map could accelerate fine mapping and map-based cloning of certain genes of cultivated strawberry.     

Changes in plasma prolactin and growth hormone concentrations during freshwater adaptation of juvenile chum salmon (Oncorhynchus keta) reared in seawater for a prolonged period

Freshwater adaptability of chum salmon was examined in juvenile fish reared in seawater for 4 months. The fish, weighing about 40g, were transferred directly to fresh water in October, when their cohorts are migrating in the North Pacific Ocean. Plasma sodium concentration decreased from 167 mM in seawater to about 130 mM during the first 24h, and increased gradually during 2–7 days after the transfer. No immunoreactive prolactin (PRL) was detected in the plasma of the seawater-adapted fish nor during the first 24h in fresh water. Significant levels of PRL were detected after 2–3 days. The maximal level (2.6 ng/ml) was observed after 5 days and became undetectable again after 7 days; no significant correlation was seen between the changes in plasma sodium and PRL levels during the transfer. Plasma growth hormone levels were relatively constant, except for a significant decrease 12h after the transfer. Although plasma thyroxine levels were highly variable during the experiment, a significant decrease and an increase were observed 12h and 5 days after the transfer, respectively. The present study indicates that juvenile chum salmon retain hyperosmoregulatory ability even after prolonged rearing in seawater. Examination of turnover rates, rather than changes in plasma levels, seems to be essential to clarify the osmoregulatory roles of the hormones.     

Improvement of larval rearing technique for mass seed production of snow crab <Emphasis Type="Italic">Chionoecetes opilio</Emphasis>

Larval rearing experiments were conducted to examine the potential for mass seed production of the snow crab Chionoecetes opilio using a total of eight 20-kL tanks. Tanks were equipped with agitators, which move the water using a rectangular blade to prevent the zoeas sinking to the bottom of the tank. Larval rearing water was treated with sodium nifurstyrenate once a week to reduce the chance of larval infection by pathogenic bacteria. Zo eas were fed with rotifers and Artemia nauplii. A total of 122 830 megalops and 16 660 first-stage crabs were produced. Thus, the potential for mass seed production of snow crab was determined. Survival rates up to the megalopal stage were high in tanks with a feeding regime that fed rotifers to larvae through an entire zoeal stage. This study also describes the fatty acid composition of snow crab larvae. It revealed that the first zoeas had a high DHA content and DHA/EPA ratio, but these values significantly decreased in the second stage zoeas and megalops. Improving the DHA content and/or DHA/EPA ratio of larvae should be important in studies on mass seed production technology of the snow crab.