Loss of melanin by eye retinal pigment epithelium cells is associated with its oxidative destruction in melanolipofuscin granules

The effect of superoxide radicals on melanin destruction and degradation of melanosomes isolated from cells of retinal pigment epithelium (RPE) of the human eye was studied. We found that potassium superoxide causes destruction of melanin in melanosomes of human and bovine RPE, as well as destruction of melanin from the ink bag of squid, with the formation of fluorescent decay products having an emission maximum at 520-525 nm. The initial kinetics of the accumulation of the fluorescent decay products is linear. Superoxide radicals lead simultaneously to a decrease in the number of melanosomes and to a decrease in concentration of paramagnetic centers in them. Complete degradation of melanosomes leads to the formation of a transparent solution containing dissolved proteins and melanin degradation products that do not exhibit paramagnetic properties. To completely degrade one melanosome of human RPE, 650 ± 100 fmol of superoxide are sufficient. The concentration of paramagnetic centers in a melanolipofuscin granule of human RPE is on average 32.5 ± 10.4% (p < 0.05, 150 eyes) lower than in a melanosome, which indicates melanin undergoing a destruction process in these granules. RPE cells also contain intermediate granules that have an EPR signal with a lower intensity than that of melanolipofuscin granules, but higher than that of lipofuscin granules. This signal is due to the presence of residual melanin in these granules. Irradiation of a mixture of melanosomes with lipofuscin granules with blue light (450 nm), in contrast to irradiation of only melanosomes, results in the appearance of fluorescent melanin degradation products. We suggest that one of the main mechanisms of age-related decrease in melanin concentration in human RPE cells is its destruction in melanolipofuscin granules under the action of superoxide radicals formed during photoinduced oxygen reduction by lipofuscin fluorophores.     

重庆市蕨类植物区系调查和分析

重庆市有野生蕨类植物47科120属604种(含变种及以下分类单位)。其科属优势明显,其中蹄盖蕨科、金星蕨科、鳞毛蕨科和水龙骨科4个科包含了49属337种,占重庆市蕨类植物属、种总数的40.83%和55.79%;特有现象明显,地方特有种十分丰富,中国特有种和地方特有种类分别达到164种和33种;蕨类植物区系具有古老、孑遗和原始性等特点,表现出一定的热带性质或热带亲缘。     

Effect of alpha-fetoprotein on lifespan of old mice

Alpha-fetoprotein (AFP) is one of the best-known embryo-specific proteins. It is used to diagnose fetal abnormalities and tumors of the gastrointestinal tract and liver. AFP has pronounced immunotropic and detoxifying effect and a direct apoptotic effect on tumor cells. The treatment of mice at the oldest age in our experiments with AFP dramatically increased the survival and markedly increased the relative weight of immunotropic organs, apparently due to the general effect of AFP in improving functions of tissues and detoxifying actions. It also improved appearance and the relative weight of internal organs with a reduced age of autoaggression.     

The system of protection of the eye structures from photo damage. Screening pigments in vertebrates--melanosomes as inhibitors of photo-oxidation processes

Melanosomes from retinal pigmented epithelium readily inhibit photooxidation of lipids. This effect is due to both passive screening of light and chemical interaction of melanosomes with products of oxidation. The role of melanosomes is discussed in the system of optic and chemical protection of eye structures from photo injury. It is suggested that in other tissues (skin) melanosomes account for the similar function of optic and chemical (antioxidative) protection from the injurious effect of UV and visible light.     

Mortality as an Indicator of Aging: Possibilities and Limitations

Biophysics - Abstract—Using data gathered from 40 countries throughout a historical period covering two and a half centuries, we studied the peculiarities of age-related changes in the aging...     

两个苜蓿品种营养器官解剖结构特征比较

为了明确具有极强抗虫特性的‘草原4号紫花苜蓿’(Medicago sativa L.‘Caoyuan No.4’) 营养器官的解剖特征,该研究选择具有抗蓟马特性较强的‘草原2号杂花苜蓿’(Medicago varia Martin.‘Caoyuan No.2’)为对照,采用显微镜观察比较两品种的根、茎、叶解剖结构特征,为揭示‘草原4号紫花苜蓿’ 抗蓟马特性提供理论依据。结果显示：(1)‘草原4号紫花苜蓿’根部解剖结构的皮层薄壁细胞厚度、内皮层厚度、形成层厚度、木质部厚度和木射线宽度等5个指标均极显著高于(P＜0.01)‘草原2号杂花苜蓿’,其中木射线宽度(159.37 μm)是‘草原2号杂花苜蓿’的1.82倍。(2)‘草原4号紫花苜蓿’的茎部厚角组织厚度(21.4 μm)极显著高于‘草原2号杂花苜蓿’(P＜0.01),而韧皮部宽度、髓直径却均极显著低于‘草原2号杂花苜蓿’(P＜0.01)。(3)‘草原4号紫花苜蓿’叶片解剖构造的7个指标均极显著高于‘草原2号杂花苜蓿’(P＜0.01),其中栅栏组织层数(2～3层)极明显地高于‘草原2号杂花苜蓿’(1~2层)。研究表明,‘草原4号紫花苜蓿’的组织结构特征具有明显的抗虫特征,且其组织的抗虫特征比‘草原2号杂花苜蓿’更为突出。