Genomic structure, functional comparison, and tissue distribution of mouse Cd59a and Cd59b

CD59 is a crucial complement regulatory protein that inhibits the terminal step of the complement activation cascade by interfering with the binding of C9 to C5b-8, thus preventing the formation of the membrane attack complex (MAC). We recently reported that the mouse genome contains two Cd59 genes, while the human and rat genomes each contain only one Cd59 gene (Qian et al. 2000). Here, we describe the genomic structure, comparative activity, and tissue distribution of these two mouse genes, designated Cd59a and Cd59b. The mouse Cd59 genes encompass a total of 45.6 kb with each gene having four exons. Cd59a spans 19 kb, and Cd59b spans 15 kb, with approximately 11.6 kb of genomic DNA separating the two genes. The overall sequence similarity between Cd59a and Cd59b is approximately 60%. The sequence similarity between exon 2, exon 3, and exon 4 and the respective flanking regions between the two genes is over 85%, but exon 1 and its flanking regions are totally different. Comparative studies of the activity of both genes as inhibitors of MAC formation revealed that Cd59b has a specific activity that is six times higher than that of Cd59a. Using polyclonal antibodies specific to either Cd59a or Cd59b, we showed that Cd59a and Cd59b are both widely expressed in the kidneys, brain, lungs, spleen, and testis, as well as in the blood vessels of most mouse tissues. Interestingly, testicular Cd59a appeared to be expressed exclusively in spermatids, whereas Cd59b was expressed in more mature sperm cells. These results suggest that even though Cd59a and Cd59b are expressed in multiple tissues, they may play some different roles, particularly in reproduction. Received: 9 February 2001 / Accepted: 18 April 2001     

Comprehensive Study of the Physicochemical Properties of Royal Jelly from Various Regions of Türkiye**

This study analysed some physicochemical and quality parameters of 176 royal jelly (RJ) samples from different regions of Türkiye, collected over different years and seasons. According to the obtained results, the moisture percentage varied between 47.36 % and 69.58 %, with no statistically significant differences seen across various seasons and areas (p>0.05). The average value of 10-hydroxy-2-decenoic acid (10-HDA), which varies according to factors such as season, region, and year, was determined to be 2.32 %. It was also seen that this value was close to the international standard. The values of total acidity ranged from 28–58 mL 1 N NaOH/100 g. Furthermore, statistical significance (p<0.001) was observed for the year-region interaction in relation to 10-HDA and total acidity. The pH measurement results for all samples confirmed the acidic nature of the samples and resulted in a range between 3.45 and 3.80. And the pH variability was also found to be statistically significant for years (p=0.002) and regions (p=0.011). Finally, the correlation analysis between moisture (%), 10-HDA (%), total acidity, and pH revealed no statistically significant or strong differences. This comprehensive study, supported by statistical analyses, is thought to be a useful reference for future research on RJ.     

A temperature–concentration (T–X) phase diagram calculated using the mean field theory for liquid crystals

Phase-line equations for smectic–hexatic phase transitions in liquid crystals were derived using the Landau phenomenological theory. In particular, second-order transitions for the smectic-A–smectic-C (SmA–SmC) and hexatic-B–hexatic-F (or HexI) transitions were studied and the tricritical points for these transitions were located. The calculated phase-line equations were fitted (using experimental data for various liquid crystals) to construct a generalized T–X phase diagram. It was shown that the T–X phase diagram calculated from the free energy adequately describes the observed behavior of liquid crystals during smectic–hexatic transitions.     

TLD characteristic of glass,feldspathic and lithium disilicate ceramics

Thermoluminescence (TL) emission of dental ceramics could be potentially used for retrospective dosimetry purposes as this allows a quick and reliable dose assessment in case of nuclear accident or bad use of a nuclear attack. This paper reports on the chemical and luminescence characterization of glass, feldspathic and lithium disilicate glass ceramic (LS₂). Swedish and Turkish dental ceramics supplied by Vivadent Ivoclar considering: (i) the dose response in the range 10 Gy to 6.9 kGy which displays a linear dose?response at low dose values up to 36 Gy (glass and feldspathic ceramics) and shows sublinear behavior from 12 Gy to 6 kGy (lithium disilicate glass ceramics), (ii) a reproducibility of the TL signal in which the area under the glow curve increased about 25% after 10 cycles for glass and lithium disilicate ceramics and increased about 30% after seven cycles for feldspathic ceramics, (iii) stability of the luminescence emission with the elapsed time and (iv) effect of the heating rate. Glass, lithium disilicate and feldspathic ceramics display a complex UV‐blue glow emission that can be respectively fitted to five and four groups of components assuming first‐order kinetics behavior.     

Genetic Differentiation Among Peripheral Populations of Bombina bombina from Thrace and Anatolia: An Allozyme Analysis

Genetic structures of Bombina bombina populations, located as peripheral isolates in Turkish Thrace and northwestern Anatolia, were analyzed by polyacrylamide gel electrophoresis using 20 allozyme loci, to investigate the populations’ current genetic variation and possible colonization history. Significant genetic variability was detected in most of the loci and all populations. Allozyme pairwise F _ST matrices and distribution of allele frequencies indicate their very close genetic relationships and relatively recent formation. Mean genetic distance values between Thracian and Anatolian populations indicate a Middle or Upper Pleistocene lineage separation before the formation of the Bosporus as an isolating geographic barrier. All the samples show substantial heterozygosity excess, and there was statistically significant evidence of recent bottlenecks. The extent and patterns of genetic divergence indicate that the Anatolian and Thracian populations have probably experienced bottlenecks, and incipient speciation may have occurred in Anatolian populations of B. bombina.     

Radiation shielding parameters of some antioxidants using Monte Carlo method

In this paper, radiation shielding parameters such as mass attenuation coefficients and half value layer (HVL) of some antioxidants are investigated using MCNPX (version 2.4.0). The validation of the generated MCNPX simulation geometry for antioxidant structures is provided by comparing the results with standard WinXcom data for radiation mass attenuation coefficients of antioxidants. Very good agreement between W?NXCOM and MCNPX was obtained. The results from the validated geometry were used to calculate the shielding parameters of different antioxidants. The radiation attenuation properties of each antioxidant were compared with each other. The results showed that, on average, the highest and the lowest radiation mass attenuation coefficients were observed on hesperidin and delphinidin chloride, respectively. It can be concluded that Monte Carlo simulation is a strong tool and an alternate method where experimental investigations are not possible and a standard simulation setup can be used in further studies for different biological structures. It can also be concluded that the obtained results from this study are very useful for radiology and radiotherapy applications where antioxidants are frequently used.