Deformation and blemishing of pearls caused by bacteria

Bacteria cause deformation and blemishing in pearls, and we investigate this relationship. We examined pearls derived from Pinctada margaritifera, Pinctada maxima, and Pinctada fucata, and determined the location of bacteria using histopathological and immunohistochemical techniques and 16S ribosomal RNA (rRNA) sequence analyses. The most remarkable change was the inflammatory reaction located between the pearl nucleus and the nacreous layer, composed of hemocytic infiltration with melanization, periostracum, and fibrous aragonite-like structures. These anomalous changes were limited to abnormal sites, and such inflammatory reaction sites are a major factor in the formation of pearl abnormalities. Bacteria were detected from the inflammatory sites and are suspected as the causative agent. Most of these bacteria were anaerobic.     

Two species of seabirds foraged in contrasting marine habitats across the cold-water belt along the coast of northern Hokkaido in the southwestern Okhotsk Sea

To understand the environmental factors affecting the density of foraging seabirds across the cold-water belt in the southwestern Okhotsk Sea, we conducted a 1-day (180-km transect length) shipboard seabird survey off the northeastern coast of Hokkaido during summer in 2019, along with acoustic observations of potential prey (zooplankton and fish) biomass, thermosalinograph measurements, and CTD observations. Planktivorous short-tailed shearwaters Ardenna tenuirostris (66% of total seabirds) and piscivorous rhinoceros auklets Cerorhinca monocerata (28%) were predominant, but foraged in contrasting habitats. A large foraging flock of shearwaters was observed in the cold-water belt zone, including its front with coastal Soya Warm Current Water and the offshore Fresh Surface Okhotsk Sea Water, where surface chlorophyll a concentrations were the highest but not related to their prey (zooplankton) biomass at any spatial scale between 4.6 and 9.2 km. In contrast, the density of auklets was high in the coastal Soya Warm Current Water, where the acoustically determined fish biomass was large, and showed a positive relationship with the fish biomass especially in the lower layer (29–104 m depth) at any spatial scale. This species-specific difference in response to prey biomass might be related to prey-searching behaviors; i.e., rhinoceros auklets search prey underwater visually, but short-tailed shearwater can use both visual and olfactory cues to locate zooplankton patches from the air.

     

Characterization of monoclonal antibodies against the second-generation schizonts of Leucocytozoon caulleryi

Monoclonal antibodies (MAbs), R1 and M5, were established against the second-generation schizont of Leucocytozoon caulleryi (L. caulleryi). Both antibodies reacted to membrane and internal structure proteins of the second-generation schizont by immunofluorescence microscopy. Molecular weight of the second-generation schizont (2GS) antigen was analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. At least 40 protein bands were detected in 2GS antigen by SDS-PAGE under reduced condition and ranged from 10 to 270 kDa. MAb R1 reacted to polypeptides of 150-268 kDa in 2GS antigen, whereas MAb M5 did with that of 66 kDa. Injection with a protein of 2GS antigen fractionated by affinity chromatography using MAbs R1 and M5 protected chickens against challenge with sporozoites of L. caulleryi. These results suggest that MAbs, R1 and M5, recognize 2GS antigen of L caulleryi.     

Variation of the agr locus in Staphylococcus aureus isolates from cows with mastitis

Staphylococcus aureus isolates from mastitic cow's milk were examined for production of alpha-hemolysin and protein A and their accessory gene regulator (agr locus) was analyzed. An inverse relationship between alpha-hemolysin and protein A production was found in most of the 76 isolates, suggesting that the isolates tested may be classified into group I (high alpha-hemolysin/low protein A), II (low alpha-hemolysin/high protein A), or III (low alpha-hemolysin/low protein A). The agr locus, which consists of hld, agrB, agrD, agrC, and agrA, was detected in most of the 78 isolates including two reference strains (Wood 46 and Cowan I) by polymerase chain reaction (PCR). When the PCR products for agr locus of 22 isolates from groups I and II were digested with restriction enzyme MboI, seven bands of the expected lengths were recognized in strain Wood 46, but not in the other isolates tested. Nucleotide sequence analysis of PCR products from six isolates revealed that the agr locus sequence of strain Wood 46 corresponded to that of the published sequence data, but the other five isolates from groups I and II diverged at agrB and agrD sequences and thus the deduced amino acid sequences. These variations of agr locus in S. aureus bovine isolates differed from those reported by Ji et al. [Science 276 (1997) 2027].     

Plasma concentration of vitamin C in dogs with a portosystemic shunt

Most mammals, including dogs, synthesize vitamin C in the liver. We measured the plasma concentration of vitamin C to assess the body vitamin C status in 15 dogs with a portosystemic shunt (PSS). The plasma biochemical parameters indicated liver abnormalities in all the dogs. In contrast, the plasma concentration of vitamin C ranged from 2.21 to 9.03 mg/L in the 15 dogs and was below the reference range (3.2 to 8.9 mg/L) in only 2 dogs. These findings suggest that vitamin C status is not impaired in dogs with PSS.     

Role of serum myostatin during the lactation period

Myostatin, also known as GDF-8 (Growth/Differentiation Factor-8), is a member of the TGF-beta superfamily that negatively regulates skeletal muscle mass in mammals. Mutation of the myostatin gene in mice, cattle, and humans causes a massively developed skeletal muscle, characterized by muscle hypertrophy and hyperplasia. Although myostatin is predominantly expressed in skeletal muscle tissue, several recent studies have shown the presence of myostatin protein in blood and suggested a possible role for circulating myostatin in the regulation of skeletal muscle mass. In the present study, we examined changes in the levels of active form myostatin (13 kDa) in serum after birth by Western blot analysis to predict the role of serum myostatin in early postnatal muscle growth in the rat. Interestingly, the amount of active form myostatin in serum increased after birth and then decreased along with ageing after weaning. To clarify the role of increased serum myostatin during the postnatal period, we administrated follistatin, an inhibitor of myostatin activity, into postnatal rats intraperitoneally just after birth. Follistatin-administration during the postnatal period caused selective hypertrophy of type II muscle fibers in the soleus muscle. These results demonstrate that myostatin in serum acts on skeletal muscle and negatively regulates early postnatal muscle growth.