Development of a complex anti-radiation protective drug

The article reports results of development of a drug for the prevention and treatment of radiation lesions in animals based on radio modified microorganisms E. coli PL-6 and B. bifidum 1. Aimed at target changing of metabolism, bacteria were exposed to gamma irradiation at doses from 1 to 20 kGy, studying the interaction of microorganisms in the consortium, as well as the safety of produced drugs. Irradiation of E. coli at a dose of 2 kGy led to the appearance of individual cells with polymorphism and having a length exceeding the initial size by 3-7 times. The irradiation of B. bifidum 1 at a dose of 4 kGy contributed to the formation for atypical, polychromic cells, multiple darkening of pigment granules and cell fragments as a result of destruction of microorganisms. The original E. coli PL-6 did not produce the enzymes superoxide dismutaseand catalase, but the metabolites of radiomodified strains of E. coli PL-6 (R10) contained 0.97±0.09 m.c.M/g SOD and 27.38±0.59 mcat/g/ml of catalase activity. In the metabolites of radio-resistant bifidobacteria, as compared with the initial ones, a 1.45-fold excess of peroxidase was recorded.

Protein kinase A regulation of pigment granule motility in retinal pigment epithelial cells from fish, Lepomis spp.

Retinomotor movements include elongation and contraction of rod and cone photoreceptors, and mass migration of melanin-containing pigment granules (melanosomes) of the retinal pigment epithelium (RPE) within the eyes of fish, frogs, and other lower vertebrates. Eyes of these animals do not contain dilatable pupils; therefore the repositioning of the rods and cones and a moveable curtain of pigment granules serve to modulate light intensity within the eye. RPE from sunfish (Lepomis spp.) can be isolated from the eye and dissociated into single cells, allowing in vitro studies of the cytoskeletal and regulatory mechanisms of organelle movement. Pigment granule aggregation from distal tips of apical projections into the cell body can be triggered by the application of underivatized cAMP, and dispersion is effected by cAMP washout in the presence of dopamine. While the phenomenon of cAMP-dependent pigment granule aggregation in isolated RPE was described many years ago, whether cAMP acts through the canonical cAMP-PKA pathway to stimulate motility has never been demonstrated. Here, we show that pharmacological inhibition of PKA blocks pigment granule aggregation, and microinjection of protein kinase A catalytic subunit triggers pigment granule aggregation. Treatment with a cAMP agonist that activates the Rap GEF, Epac (Effector protein activated by cAMP), had no effect on pigment granule position. Taken together, these results confirm that cAMP activates RPE pigment granule motility by the canonical cAMP-PKA pathway. Isolated RPE cells labeled with antibodies against PKA RIIα and against PKA-phosphorylated serine/threonine amino acids show diffuse, punctate labeling throughout the RPE cell body and apical projections. Immunoblotting of RPE lysates using the anti-PKA substrate antibody demonstrated seven prominent bands; two bands in particular at 27 and 64 kD showed increased levels of phosphorylation in the presence of cAMP, indicating their phosphorylation could contribute to the pigment granule aggregation mechanism.

Core–shell nanospheres behind the blue eyes of the bay scallop Argopecten irradians

The bay scallop Argopecten irradians (Mollusca: Bivalvia) has dozens of iridescent blue eyes that focus light using mirror-based optics. Here, we test the hypothesis that these eyes appear blue because of photonic nanostructures that preferentially scatter short-wavelength light. Using transmission electron microscopy, we found that the epithelial cells covering the eyes of A. irradians have three distinct layers: an outer layer of microvilli, a middle layer of random close-packed nanospheres and an inner layer of pigment granules. The nanospheres are approximately 180 nm in diameter and consist of electron-dense cores approximately 140 nm in diameter surrounded by less electron-dense shells 20 nm thick. They are packed at a volume density of approximately 60% and energy-dispersive X-ray spectroscopy indicates that they are not mineralized. Optical modelling revealed that the nanospheres are an ideal size for producing angle-weighted scattering that is bright and blue. A comparative perspective supports our hypothesis: epithelial cells from the black eyes of the sea scallop Placopecten magellanicus have an outer layer of microvilli and an inner layer of pigment granules but lack a layer of nanospheres between them. We speculate that light-scattering nanospheres help to prevent UV wavelengths from damaging the internal structures of the eyes of A. irradians and other blue-eyed scallops.

Conjunctival tattoo with inadvertent ocular globe penetration and vitreous involvement: Clinico-pathological correlation and scanning electron microscopy X-ray microanalysis

Purpose: The aim is to report a case of conjunctival tattooing with inadvertent injection of tattoo ink into the vitreous cavity and its consequences, the scanning electron microscopy X-ray microanalysis of the ink components, and the microscopic findings of the affected conjunctiva and vitreous. Methods: Descriptive case report. Results: A 32-year-old man complained of ocular pain and blurred vision after undergoing a subconjuctival red ink tattoo in his left eye. Ophthalmologic examination revealed best corrected visual acuity of 20/80 and intraocular pressure of 26 mmHg. Pain was elicited with eye movements. The bulbar conjunctiva was colored intense red. In the anterior chamber, pigment granules and filaments were suspended on the aqueous humor, and lens capsule was also stained red. Ultrasonography showed high-density non-mobile echoes in the conjunctiva; anterior chamber and vitreous cavity revealed high-density mobile echoes corresponding to pigment particles. Conjunctival tattoo with inadvertent globe penetration was the clinical diagnosis. The patient received medical and surgical treatment. Histopathological examination of the conjunctiva showed red pigment globular deposits within the stroma, and neutrophils and sparse histiocytes with similar intracytoplasmic pigment granules were seen. No granulomatous foreign body reaction was noticed. Vitreous material contained pigment granules; no inflammatory cells were observed. Scanning electron microscopy X-ray microanalysis of the tattoo red ink revealed significant signals of iron, barium, and copper. Conclusion: Conjunctival tattoo is a new form of body decoration gaining worldwide popularity. This procedure is performed by untrained professionals causing severe ocular complications including blindness. Safety regarding tattoo ink needs further study as the composition varies among colors. Strict regulations on this matter should be considered.

Colouration in fishes

A large number of teleostean fishes is brightly and brilliantly coloured. Colouration is due to presence of chromatophores containing various kinds of pigment granules in their skin and scales. Colouration in fishes provides them power of adjustment with surrounding and also enables them to survive. Various factors like temperature, light, diet, stimuli, nervous and hormonal changes affect functioning of chromatophores, leading to colour coordination and dispersion. Colour pattern in fishes is used for concealment camouflage, communication, warning and sexual recognition, besides having taxonomic importance.

Screening pigment of the camera eyes of stalkeyed mollusks (Pulmonata, Stylommatophora) with different light preferences

Morphological properties of the granules of the screening pigment in the retinae of camera eyes of gastropod mollusks with different light preferences were studied. It was demonstrated that the pigment granules of mollusks can differ by color and size but do not differ by structure, electron density and form. Light conditions of mollusks’ habitats can influence on the amount of the screening pigment, which in its turn does not affect resolving ability of the eyes.

Stimulation of microtubule-based transport by nucleation of microtubules on pigment granules

Microtubule (MT)-based transport can be regulated through changes in organization of MT transport tracks, but the mechanisms that regulate these changes are poorly understood. In Xenopus melanophores, aggregation of pigment granules in the cell center involves their capture by the tips of MTs growing toward the cell periphery, and granule aggregation signals facilitate capture by increasing the number of growing MT tips. This increase could be explained by stimulation of MT nucleation either on the centrosome or on the aggregate of pigment granules that gradually forms in the cell center. We blocked movement of pigment granules to the cell center and compared the MT-nucleation activity of the centrosome in the same cells in two signaling states. We found that granule aggregation signals did not stimulate MT nucleation on the centrosome but did increase MT nucleation activity of pigment granules. Elevation of MT-nucleation activity correlated with the recruitment to pigment granules of a major component of MT-nucleation templates, γ-tubulin, and was suppressed by γ-tubulin inhibitors. We conclude that generation of new MT transport tracks by concentration of the leading pigment granules provides a positive feedback loop that enhances delivery of trailing granules to the cell center.

Pigmented Cells in the Pineal Gland of Female Viscacha (Lagostomus maximus maximus): A Histochemical and Ultrastructural Study

The presence of pigment has been demonstrated in different nervous structures such as those of retina, substantia nigra, and locus coeruleus. These pigments have also been described in the pineal gland of different mammal species. Histochemical and ultrastructural studies of the pineal gland of female viscacha (Lagostomus maximus maximus) were performed to analyze the presence of pigmented cells under natural conditions and to evaluate a probable relation between pigment content and glandular activity during pregnancy. The following techniques were applied: hematoxylin-eosin, phosphotungstic acid-hematoxylin, Masson-Fontana silver, DOPA histochemistry, Schmorl’s reaction and toluidine blue. Estradiol and progesterone serum levels were determined by RIA. The ultrastructural features of the pineal pigment granules were also analyzed. Pigment granules were observed in a random distribution, but the pigmented cells were frequently found near blood vessels. The pineal pigment was histochemically identified as melanin. Differences in the amount of pigmented cells were found between pregnant and nonpregnant viscachas. The ultrastructural analysis revealed the presence of premelanosomes and melanosomes. Estradiol and progesterone levels vary during pregnancy. In conclusion, the changes in the amount of pigment content and hormone levels may indicate that the pineal gland of female viscacha is susceptible to endocrine variations during pregnancy.