Ca2+-induced fusion of Golgi-derived secretory vesicles isolated from rat liver

During the transport of plasma proteins from the cytoplasma of hepatocytes to the extracellular fluid srnall vesicles may act as shuttles between the Golgi complex and the plasma membrane. This type of intracellular transfer is weil established for various secretory cells and may be adopted also for the hepatocyte. Recent investigations have shown that secretory vesicles fuse with each other during secretion in mast cells [4] exocrine [5,6] and endocrine pancreatic tissue [7]. The intervesicular fusion provides a tool for studies on membrane fusion, since Golgi-derived vesicles can be isolated from the hepatocyte and their interaction with various agents, suggested to trigger membrane fusion, can be monitored by freeze-cleaving

Fényérzékeny molekulák és fotoreceptorok a gerincesek retinájában és tobozmirigyében = Photosensitive molecules and photoreceptors in the vertebrate retina and pineal gland

Míg az emlősök legtöbbjében, amelyekben legalább kétféle színérzékenységű fotoreceptor található, kimutatható a transzdifferenciáció, vagyis a rövidhullám-érzékeny (kék) csapok korai megjelenése, és ezek egy részében a középhullám-érzékeny (zöld) pigment későbbi expressziója. Az eredeti kék pigment eltűnése eredményezi a definitív zöld csapokat, míg azok, amelyekben a zöld pigment egyáltalán nem jelenik meg, adják a kék csap-populációt. Elvetettük a hipotézist, hogy a monokromatikus fajokan is a kék-pigment expresszióján keresztül vezet az út. Felnőttben is előfordulnak két pigmentet tartalmazó csapok. A transzdifferenciáció (csap-fejlődés) nem áll meg újszülött korban, hanem folytatódik felnőttben is. Ezek idegi őssejtek, amelyek a retina regenerációjában játszhatnak szerepet (anti-PCNA). A csapok differenciálódásában közrejátszó tényezők közül a BDNF, az NT-3 és a TrkB szerepet játszanak a kék-zöld átalakulásban. Tenyésztés és immuncitokémia bizonyítja, hogy a kék csapok fejlődéséhez elegendő a megfelelő feltételek fennállása. A zöld csapok megjelenéséhez azonban az említett tényezők is szükségesek. A nem-vizuális fotoreceptorok feladata a diurnális ritmus beállítása. A bennük lévő cryptochromok kék-érzékenyek. Az ékszakai megvilágítás patológiás hatásait (emlőrák, colorectalis tumorok, stb.) a pineális melatonin gátlása okozza. Ezek redukálhatók kék fény-mentes megvilágítással, azaz megfelelő színszűrők használatával. | In mammals that possess two color-specific photoreceptors, transdifferentiation is present. That means the early appearance of short wave (blue) cones and the later expression of middle wave (green) pigment in some of them. The disappearance of the original blue pigment results in the development of definitive green cones. Those in which no green pigment appears at all will make the blue cone population. The hypothesis that in monochromatic species green cones come about through the transitory appearance of blue pigment has been rejected. Dual cones expressing two visual pigments occur also in adults. Obviously, the transdifferentiation does not come to an end in the early postnatal period, rather it goes on in the adulthood. These might be neuronal stem cells playing a role in the regeneration of the retina (anti-PCNA). Of the factors having a role in the cone differentiation, BDNF, NT-3 and TrkB seem to be effective in the blue-green transition. Immunocytochemistry and tissue culture prove that proper culture technique is enough for the development of blue cones, however the above factors are indispensable for the green cones. Non-visual photoreceptors play a role in the entrainment of the diurnal clock. Their cryptochromes proved to be blue-sensitive. The pathologic effects of night work are attributed to the inhibition of pineal melatonin. The adverse reactions might be reduced with blue light-free illumination, with proper color filters

Fusion of secretory vesicles isolated from rat liver

Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences

Research on bodies of the executed in German anatomy: An accepted method that changed during the Third Reich. Study of anatomical journals from 1924 to 1951

While it is known that bodies of the executed were used for anatomical research in Germany during the Third Reich, it is unclear whether this type of work was unique to the time period or more common in Germany than elsewhere. The dissected persons and the anatomists involved have not been fully investigated. This study of anatomical journals from 1924 to 1951 shows that 166 out of 7,438 [2.2%] German language articles mentioned the use of “material” from the bodies of executed persons. In comparison, only 2 out of 4,702 English language articles explicitly mentioned bodies of the executed. From 1924 to1932, 33 of a total of 3,734 [1%] German articles listed the use of the executed. From 1933 to 1938 the number rose to 46 out of 2,265 [2%], and increased again from 1939 to 1945 to 73 out of 984 [7%]. After the war 15 out of 455 [3%] still dealt with “material” from the executed. German anatomists' familiarity with the use of the executed as a standard for healthy tissues even before 1933 may have contributed to the ease with which they accepted the “opportunities” (large‐scale studies and research on women) presented to them by unlimited access to bodies of the executed provided by the abusive National Socialist (NS) legislation and continued using them for some years after the war. German postwar anatomy was built in part on the bodies of NS victims. Information given in some publications will help with further identification of these victims. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97274/1/22107_ftp.pd

αB Crystallin Is Apically Secreted within Exosomes by Polarized Human Retinal Pigment Epithelium and Provides Neuroprotection to Adjacent Cells

αB Crystallin is a chaperone protein with anti-apoptotic and anti-inflammatory functions and has been identified as a biomarker in age-related macular degeneration. The purpose of this study was to determine whether αB crystallin is secreted from retinal pigment epithelial (RPE) cells, the mechanism of this secretory pathway and to determine whether extracellular αB crystallin can be taken up by adjacent retinal cells and provide protection from oxidant stress. We used human RPE cells to establish that αB crystallin is secreted by a non-classical pathway that involves exosomes. Evidence for the release of exosomes by RPE and localization of αB crystallin within the exosomes was achieved by immunoblot, immunofluorescence, and electron microscopic analyses. Inhibition of lipid rafts or exosomes significantly reduced αB crystallin secretion, while inhibitors of classic secretory pathways had no effect. In highly polarized RPE monolayers, αB crystallin was selectively secreted towards the apical, photoreceptor-facing side. In support, confocal microscopy established that αB crystallin was localized predominantly in the apical compartment of RPE monolayers, where it co-localized in part with exosomal marker CD63. Severe oxidative stress resulted in barrier breakdown and release of αB crystallin to the basolateral side. In normal mouse retinal sections, αB crystallin was identified in the interphotoreceptor matrix. An increased uptake of exogenous αB crystallin and protection from apoptosis by inhibition of caspase 3 and PARP activation were observed in stressed RPE cultures. αB Crystallin was taken up by photoreceptors in mouse retinal explants exposed to oxidative stress. These results demonstrate an important role for αB crystallin in maintaining and facilitating a neuroprotective outer retinal environment and may also explain the accumulation of αB crystallin in extracellular sub-RPE deposits in the stressed microenvironment in age-related macular degeneration. Thus evidence from our studies supports a neuroprotective role for αB crystallin in ocular diseases

Histological Evaluation of Diabetic Neurodegeneration in the Retina of Zucker Diabetic Fatty (ZDF) Rats

In diabetes, retinal dysfunctions exist prior to clinically detectable vasculopathy, however the pathology behind these functional deficits is still not fully established. Previously, our group published a detailed study on the retinal histopathology of type 1 diabetic (T1D) rat model, where specific alterations were detected. Although the majority of human diabetic patients have type 2 diabetes (T2D), similar studies on T2D models are practically absent. To fill this gap, we examined Zucker Diabetic Fatty (ZDF) rats - a model for T2D - by immunohistochemistry at the age of 32 weeks. Glial reactivity was observed in all diabetic specimens, accompanied by an increase in the number of microglia cells. Prominent outer segment degeneration was detectable with changes in cone opsin expression pattern, without a decrease in the number of labelled elements. The immunoreactivity of AII amacrine cells was markedly decreased and changes were detectable in the number and staining of some other amacrine cell subtypes, while most other cells examined did not show any major alterations. Overall, the retinal histology of ZDF rats shows a surprising similarity to T1D rats indicating that despite the different evolution of the disease, the neuroretinal cells affected are the same in both subtypes of diabetes