Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase

A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1.     

Enhancement of CO2 tolerance of Chlorella vulgaris by gradual increase of CO2 concentration

Summary Chlorella vulgaris UTEX259 was cultivated using two different methods of gas supply. In one method the CO₂ concentration in bubbled gas was held constant and in the other method it was increased gradually. Algal growth was almost linear after a short period of lag phase in both methods. With the constant CO₂ concentration, the CO₂ fixation rate in the linear growth phase decreased over 10%(v/v) CO₂, while the rate increased up to 6% CO₂. However, the rate was enhanced by using the latter incremental increase method, especially under a higher concentration of CO₂. The maximum rate of CO₂ fixation was 52 mg CO₂/l·h at 20% CO₂ during the gradual increase of CO₂ concentration.     

Studies onSargassum

Summary Cytological comparisons of homologous tissues in blades and stipes by stereological analysis have shown differences exist between blade and stipe organs inSargassum. Based on measurements of total thylakoid and cristae membrane surface areas in these organs blades were found to contain 61% more thylakoid membrane surface and 65% more cristae membrane than stipes on a per unit volume basis. Assuming photosynthesis and respiration are directly related to the surface area of the internal membranes in the respective organelles it is possible to predict that blades will have a 61% greater photosynthetic and a 65% greater respiratory potential. Photosynthetic and respiratory rates for blades and stipes were determined manometrically and show a 62% greater photosynthetic and 59% greater respiratory rates for the blade tissues agreeing very well with predicted values.Present evidence indicates that photosynthetic and respiratory rate differences observed in the blades and stipes inSargassum are the result of increased membrane surface areas in the larger cells of the tissues which make up the blade. The basic cell structure,i.e., the percent volume of cell cytoplasm occupied by each organelle, is similar in homologous tissues of both organs regardless of cell size. Therefore physiological differences between the two organs are primarily due to changes in cell size and not in basic cell construction. This provides an interesting mechanism for producing physiological differences without changing basic cell structure in the organs of this plant.     

Use of moving aeration membrane bioreactor for the efficient production of tissue type plasminogen activator in serum free medium

A moving aeration-membrane (MAM) bioreactor was employed for the production of 2 μg/mL of tissue type Plasminogen Activator (tPA) in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating conditions, shear stress was as low as 0.65 dynes/cm² at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2 μg tPA/mL while maintaining a high cell density of 1.0×10⁷ viable cells/mL.     

The protein-tyrosine kinase Syk interacts with the C-terminal region of tensin2

Syk is a 72-kDa protein-tyrosine kinase that regulates signaling through multiple cell surface receptors including those for antigens, immunoglobulins and proteins of the extracellular matrix. As part of its function, Syk binds a variety of downstream effectors through interactions that are often mediated by motifs that recognize phosphotyrosines. In a search for novel Syk-interacting proteins by yeast two-hybrid analysis, we identified tensin2 as a Syk-binding protein. Syk interacts with a fragment of tensin2 located near the C-terminus that contains SH2 and PTB domains. In epithelial cells, tensin2 localizes both to focal adhesions and to large cytoplasmic puncta. It is within these punctuate structures that Syk and tensin2 are co-localized. The clustering of Syk within these structures leads to its phosphorylation on tyrosine.     

Characterization of a serine proteinase mediating encystation of Acanthamoeba

Members of the genus Acanthamoeba, amphizoic protozoan parasites, are causative agents of granulomatous amoebic encephalitis and amoebic keratitis. Proteinases play a role in various biologic actions in Acanthamoeba, including host tissue destruction, pathogenesis, and digestion of phagocytosed food. Interestingly, we found that encystation of Acanthamoeba was inhibited by the serine proteinase inhibitor phenylmethanesulfonyl fluoride. In this study, we characterize a serine proteinase that is involved in mediating the encystation of Acanthamoeba. This encystation-mediating serine proteinase (EMSP) is shown to be highly expressed during encystation by real-time PCR and Western blot analysis. Chemically synthesized small interfering RNA against EMSP inhibited the expression of EMSP mRNA and significantly reduced the encystation efficiency of Acanthamoeba. An EMSP-enhanced green fluorescent protein fusion protein localized to vesicle-like structures within the amoeba. Using LysoTracker analysis, these vesicular structures were confirmed to be lysosomes. After incubation of the transfected amoeba in encystment media, small fluorescent vesicle-like structures gathered and formed ball-like structures, which were identified as colocalizing with the autophagosome. Taken together, these results indicate that EMSP plays an important role in the differentiation of Acanthamoeba by promoting autolysis.     

Photoacoustic Imaging of Breast Microcalcifications: A Preliminary Study with 8-Gauge Core-Biopsied Breast Specimens

Background

We presented the photoacoustic imaging (PAI) tool and to evaluate whether microcalcifications in breast tissue can be detected on photoacoustic (PA) images.

Methods

We collected 21 cores containing microcalcifications (n = 11, microcalcification group) and none (n = 10, control group) in stereotactic or ultrasound (US) guided 8-gauge vacuum-assisted biopsies. Photoacoustic (PA) images were acquired through ex vivo experiments by transmitting laser pulses with two different wavelengths (700 nm and 800 nm). The presence of microcalcifications in PA images were blindly assessed by two radiologists and compared with specimen mammography. A ratio of the signal amplitude occurring at 700 nm to that occurring at 800 nm was calculated for each PA focus and was called the PAI ratio.

Results

Based on the change of PA signal amplitude between 700 nm and 800 nm, 10 out of 11 specimens containing microcalcifications and 8 out of 10 specimens without calcifications were correctly identified on blind review; the sensitivity, specificity, accuracy, positive predictive and negative predictive values of our blind review were 90.91%, 80.0%, 85.71%, 83.33% and 88.89%. The PAI ratio in the microcalcification group was significantly higher than that in the control group (the median PAI ratio, 2.46 versus 1.11, respectively, P = .001). On subgroup analysis in the microcalcification group, neither malignant diagnosis nor the number or size of calcification-foci was proven to contribute to PAI ratios.

Conclusion

Breast microcalcifications generated distinguishable PA signals unlike breast tissue without calcifications. So, PAI, a non-ionizing and non-invasive hybrid imaging technique, can be an alternative in overcoming the limitations of conventional US imaging.