Abnormal mitochondrial cristae were experimentally generated by high doses of Apis mellifera venom in the rat adrenal cortex

In the present study, Apis mellifera venom (AmV) was tested for its ability to cause ultrastructural changes in mitochondria of rat adrenal cortex in vivo. In order to achieve this goal, different AmV treatments were performed and the effects were quantified on transmission electron micrographs. In a first experimental group, AmV injected for 30 days in low daily doses (700 μg/kg) generated important ultrastructural changes in zona fasciculata. The mitochondrial ultrastructure was not affected, but the diameters of mitochondrial cristae (MC) were reduced (57.066 ± 7.795 nm) as compared to the MC diameters in the corresponding control groups (58.596 ± 6.603 nm, and 58.503 ± 5.708 nm). In adrenal glands collected from rats injected with a single, high dose of AmV (62 mg/kg), many ultrastructural changes were described. Mitochondria with normal, tubular MC (with diameter of 58.711 ± 5.907 nm) were observed in many cells, very close to the values calculated for the corresponding control group (58.639 ± 6.117 nm). However, the striking data reported herein concerned the ability of AmV high doses to promote dramatic alterations in the ultrastructure of these particular mitochondria, similar to those described in certain severe diseases. Thus, several types of abnormal mitochondria were observed, including mitochondria displaying lamellar and/or circular, concentric cristae and mitochondria devoid of cristae. The abnormal circular, concentric MC, with large inner (281.904 ± 158.588 nm) and outer (432.076 ± 230.372 nm) diameters, appeared to be the most stable form of MC in the adrenal cortex after the acute treatment with AmV. Among other ultrastructural aspects, these important changes indicated a high level of cytotoxicity of AmV in adrenocortical cells following in vivo experimental poisoning.     

The evidence of Tobacco rattle virus impact on host plant organelles ultrastructure

Tobraviruses, like other (+) stranded RNA viruses of plants, replicate their genome in cytoplasm and use such usual membranous structures like endoplasmic reticulum. Based on the ultrastructural examination of Tobacco rattle virus (TRV)-infected potato and tobacco leaf tissues, in this work we provide evidence of the participation of not only the membranous and vesicular ER structures but also other cell organelles during the viral infection cycle. Non-capsidated TRV PSG particles (potato isolate from the Netherlands) (long and short forms) were observed inside the nucleus while the presence of TRV capsid protein (CP) was detected in the nucleus caryolymph and within the nucleolus area. Both capsidated and non-capsidated viral particles were localized inside the strongly disorganized chloroplasts and mitochondria. The electron-dense TRV particles were connected with vesicular structures of mitochondria as well as with chloroplasts in both potato and tobacco tissues. At 15–30 days after infection, vesicles filled with TRV short particles were visible in mitochondria revealing the expanded cristae structures. Immunodetection analysis revealed the TRV PSG CP epitope inside chloroplast with disorganized thylakoids structure as well as in mitochondria of different tobacco and potato tissues. The ultrastructural analysis demonstrated high dynamics of the main cell organelles during the TRV PSG–Solanaceous plants interactions. Moreover, our results suggest a relationship between organelle changes and different stages of virus infection cycle and/or particle formation.     

Effect of low level laser irradiation on the proliferation of myoblasts—the skeletal muscle precursor cells: an experimental in vitro study

The aim of this paper is to study the effect of low-level laser irradiation (LLLI) on proliferation of myoblasts in culture. Myoblasts derived from rat skeletal muscle were irradiated by He-Ne laser with different doses. Compared with nonirradiated control group, the number of myoblasts increased when the cells in normal culture conditions were exposed to the laser of specific energy density. The amount of cells with proliferating cell nuclear antigen (PCNA) positive expression and the 5-bromo-2′-deoxyuridine (BrdU) incorporation rate after laser irradiation were also higher than that of the control group, suggesting that LLLL at certain doses can effectively enhance myoblasts growth activity in vitro. This study firstly demonstrated that stimulating myoblasts to enter into proliferative stage from initial resting state was an important mechanism of regeneration and repair of injured skeletal muscle promoted by LLLI in clinical treatment.     

Ultrastructural changes to rat hippocampus in pentylenetetrazol- and kainic acid-induced status epilepticus: A study using electron microscopy

A pentylenetetrazol (PTZ)-induced status epilepticus model in rats was used in the study. The brains were studied one month after treatment. Ultrastructural observations using electron microscopy performed on the neurons, glial cells, and synapses, in the hippocampal CA1 region of epileptic brains, demonstrated the following major changes over normal control brain tissue. (i) There is ultrastructural alterations in some neurons, glial cells and synapses in the hippocampal CA1 region. (ii) The destruction of cellular organelles and peripheral, partial or even total chromatolysis in some pyramidal cells and in interneurons are observed. Several astrocytes are proliferated or activated. Presynaptic terminals with granular vesicles and degenerated presynaptic profiles are rarely observed. (iii) The alterations observed are found to be dependent on the frequency of seizure activities following the PTZ treatment. It was observed that if seizure episodes are frequent and severe, the ultrastructure of hippocampal area is significantly changed. Interestingly, the ultrastructure of CA1 area is found to be only moderately altered if seizure episodes following the status epilepticus are rare and more superficial; (iv) alterations in mitochondria and dendrites are among the most common ultrastructural changes seen, suggesting cell stress and changes to cellular metabolism. These morphological changes, observed in brain neurons in status epilepticus, are a reflection of epileptic pathophysiology. Further studies at the chemical and molecular level of neurotransmitter release, such as at the level of porosomes (secretory portals) at the presynaptic membrane, will further reveal molecular details of these changes.     

低能量激光联合压力对成骨细胞ALP活性和胞内Ca~(2+)浓度的影响

探讨低能量激光照射(1ow--level laser irradiation,LLLI)联合压力刺激对人成骨样细胞的碱性磷酸酶(alkaline phosphatase,ALP)活性和胞内Xa~(2+)浓度的变化规律的影响,揭示LLLI促进正畸牙齿压力侧骨改建的机制。将对数生长期的人成骨样细胞MG-63随机分为4组,对细胞施加压力采用Foreel四点弯曲体外细胞力学加载装置,用Ga-Al-As半导体激光器(808 nm,500 mW)进行照射。组Ⅰ(对照组):不加力,不进行激光照射。组Ⅱ(压力组):利用细胞加载装置对细胞加压力,加力板变形量为3 000 ustrain,加力时间1h。组Ⅲ(激光组):激光照射1 min,剂量3.75 J·cm。组Ⅳ(联合组):细胞加力(加力方式同组Ⅱ)后,激光照射(方式同组Ⅲ)。四组细胞均用分光光度计测量细胞内ALP活性。第二部分实验对胞内Ca~(2+)浓度变化进行测定,将MG-63细胞分为2组:压力组和激光张力组,2组细胞分别加力0,5,15,30,60 min,激光压力组再激光照射1 min后收取细胞。用荧光探针Fluo-3-AM测定成骨样细胞内Xa~(2+)浓度。结果显示第一部分实验与对照组相比,其余3组的ALP活性均明显增强(p0.05),但联合组的ALP活性分别低于压力组和激光组(p0.05)。第二部分实验显示:第1组压力引起胞内Ca~(2+)浓度随时间剧烈变化,第2组变化曲线平缓,但Xa~(2+)浓度水平两组无明显差异。由此得出结论适宜的压力和弱激光及联合应用均能增加成骨细胞的ALP活性,两者联合应用时较单独应用时成骨细胞的ALP活性稍有降低,压力组和激光压力组胞内Ca~(2+)浓度的变化曲线不同,说明在正畸牙齿的压力侧,低能量激光的应用可以降低由压力引起的成骨细胞活性增加,减少成骨,破骨相对增加,促进牙齿移动,LLLI极可能通过调节Xa~(2+)浓度的变化规律来调节成骨细胞活性。     

Ultrastructural insights into tomato infections caused by three different pathotypes of Pepino mosaic virus and immunolocalization of viral coat proteins

This paper presents studies on an ultrastructural analysis of plant tissue infected with different pathotypes of Pepino mosaic virus (PepMV) and the immunolocalization of viral coat proteins. Because the PepMV virus replicates with a high mutation rate and exhibits significant genetic diversity, therefore, isolates of PepMV display a wide range of symptoms on infected plants. In this work, tomato plants of the Beta Lux cultivar were inoculated mechanically with three pathotypes representing the Chilean 2 (CH2) genotype: mild (PepMV-P22), necrotic (PepMV-P19) and yellowing (PepMV-P5-IY). The presence of viral particles in all infected plants in the different compartments of various cell types (i.e. spongy and palisade mesophyll, sieve elements and xylem vessels) was revealed via ultrastructural analyses. For the first time, it was possible to demonstrate the presence of crystalline inclusions, composed of virus-like particles. In the later stage of PepMV infection (14 dpi) various pathotype-dependent changes in the structure of the individual organelles (i.e. mitochondria, chloroplasts) were found. The strongest immunogold labeling of the viral coat proteins was also observed in plants infected by necrotic isolates. A large number of viral coat proteins were marked in the plant conductive elements, both xylem and phloem.     

Ultrasound induces cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin

Objectives

Curcumin, a natural pigment from the traditional Chinese herb, has shown promise as an efficient enhancer of ultrasound. The present study aims to investigate ultrasound-induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin in vitro.

Methods

Nasopharyngeal carcinoma cell line CNE2 cells were incubated by 10 μm curcumin and then were treated by ultrasound for 8 s at the intensity of 0.46 W/cm². Cytotoxicity was evaluated using MTT assay and light microscopy. Mitochondrial damage was analyzed using a confocal laser scanning microcopy with Rhodamine 123 and ultrastructural changes were observed using a transmission electron microscopy (TEM).

Results

MTT assay showed that cytotoxicity induced by ultrasound treatment alone and curcumin treatment alone was 18.16 ± 2.37% and 24.93 ± 8.30%, respectively. The cytotoxicity induced by the combined treatment of ultrasound and curcumin significantly increased up to 86.67 ± 7.78%. TEM showed that microvillin disappearance, membrane blebbing, chromatin condensation, swollen mitochondria, and mitochondrial myelin-like body were observed in the cells treated by ultrasound and curcumin together. The significant collapse of mitochondrial membrane potential (MMP) was markedly observed in the CNE2 cells after the combined treatment of curcumin and ultrasound.

Conclusions

Our findings demonstrated that ultrasound sonication in the presence of curcumin significantly killed the CNE2 cells and induced ultrastructural damage and the dysfunction of mitochondria, suggesting that ultrasound treatment remarkably induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin.     

Molecular and functional diversity of vascular endothelial growth factors

Summary Members of the vascular endothelial growth factor (VEGF) family are crucial regulators of neovascularization and are classified as cystine knot growth factors that specifically bind cellular receptor tyrosine kinases VEGFR-1, VEGFR-2, and VEGFR-3 with high but variable affinity and selectivity. The VEGF family has recently been expanded and currently comprises seven members: VEGF-A, VEGF-B, placenta growth factor (PlGF), VEGF-C, VEGF-D, viral VEGF (also known as VEGF-E), and snake venom VEGF (also known as VEGF-F). Although all members are structurally homologous, there is molecular diversity among the subtypes, and several isoforms, such as VEGF-A, VEGF-B, and PlGF, are generated by alternative exon splicing. These splicing isoforms exhibit differing properties, particularly in binding to co-receptor neuropilins and heparin. VEGF family proteins play multiple physiological roles, such as angiogenesis and lymphangiogenesis, while exogenous members (viral and snake venom VEGFs) display activities that are unique in physiology and function. This review will highlight the molecular and functional diversity of VEGF family proteins.     

Occurrence and ultrastructure of Albugo candida on a new host, Arabis alpina in Saudi Arabia

A population of Arabis alpina (Brassicaceae) growing in Saudi Arabia was observed to be infected for the first time by the Oomycete, Albugo candida. Both conventional chemical fixation and high pressure freezing followed by freeze substitution (HPF/FS) were used to prepare zoosporangia, intercellular hyphae, haustoria, invading host cells and host–parasite interface of A. candida for study with both scanning and transmission electron microscopy. Both fixations gave good preservation of ultrastructural details and data from the two sample types were highly complementary. Scanning electron microscopic observation revealed that mature zoosporangia of A. candida are spherical or ellipsoidal in shape and characterized by a smooth surface and faint terminal secession scar at each end. Transmission electron microscopic observation indicated that coenocytic intercellular hyphae are located in intercellular spaces of host leaf tissue forming haustoria in host mesophyll cell. Each haustorium is connected to intercellular hyphae by a narrow, slender neck which enclosed by a collar as a response of host cell to infection. The cytoplasm of the haustorium contains different organelles characteristic of the Oomycetes. No obvious responses are observed in host cell organelles following infection which may be due to the presence of a compatibility between the host and the Oomycete. Modifications of the host plasma membrane around the haustorium are detected. Many tubular elements were found to be continuous with the extrahaustorial membrane. This appears to be the first report of the presence of these tubular elements in case of A. candida haustoria. These tubular elements may increase membrane surface area and consequently increase the efficacy of nutrients uptake by haustoria from host cell.     

Scanning and transmission electron microscopy and X-ray analysisof leaf salt glands of Limoniastrum guyonianum Boiss. under NaCl salinity

Leaf salt glands of Limoniastrum guyonianum were examined by scanning and transmission electron microscopes and energy dispersive X-ray analysis (EDAX) system, after growing for three months on sandy soil with or without 300 mM NaCl. Results showed that salt glands were irregularly scattered on both leaf sides and sunk under the epidermal level. Salt excretion occurred in both conditions and is mainly composed of calcium and magnesium in control plants, and essentially sodium and chloride in plants subjected to salt treatment. A salt gland is comprised of collecting, accumulating, and central compartments, and is made up of total thirty-two cells. The collecting cells were characterized by large central vacuoles. Accumulating cells contain numerous, large, and unshaped vacuoles and rudimentary chloroplasts. The central compartment was comprised of four basal cells and each one is surmounted by an apical cell. The basal cells are granulated, containing large nucleus, numerous mitochondria, endoplasmic reticulum, ribosomes, polyribosomes, and small vacuoles or vesicles. Equally, the apical cells are rich in organelles. Application of 300 mM NaCl to the culture medium increased vacuoles number and size, and organelles density especially the mitochondria which suggests energy requirement for ions transport. The reduction in size and number of vacuoles toward the interior of salt glands of treated plants and the fusion of the smallest ones with the plasma membrane substantiate the implication of such vacuoles in salt excretion process. The current study which is the first report on L. guyonianum salt gland has provided an in-depth understanding on structure–function relationship in the multicellular salt glands.     

High-pressure freezing and freeze-substitution fixation reveal the ultrastructure of immature and mature spermatozoa of the plant-parasitic nematode Trichodorus similis (Nematoda; Triplonchida; Trichodoridae)

The spermatozoa from testis and spermatheca of the plant-parasitic nematode Trichodorus similis Seinhorst, 1963 (Nematoda; Triplonchida; Trichodoridae) were studied with transmission electron microscopy (TEM), being the first study on spermatogenesis of a representative of the order Triplonchida and important to unravel nematode sperm evolution. Comprehensive results could only be obtained using high-pressure freezing (HPF) and freeze-substitution instead of chemical fixation, demonstrating the importance of cryo-fixation for nematode ultrastructural research. The spermatozoa from the testis (immature spermatozoa) are unpolarized cells covered by numerous filopodia. They contain a centrally-located nucleus without a nuclear envelope, surrounded by mitochondria. Specific fibrous bodies (FB) as long parallel bundles of filaments occupy the peripheral cytoplasm. No structures resembling membranous organelles (MO), as found in the sperm of many other nematodes, were observed in immature spermatozoa of T. similis. The spermatozoa from the uterus (mature or activated spermatozoa) are bipolar cells with an anterior pseudopod and posterior main cell body (MCB), which include a nucleus, mitochondria and MO appearing as large vesicles with finger-like invaginations of the outer cell membrane, or as large vesicles connected to the inner cell membrane. The peripheral MO open to the exterior via pores. In the mature sperm, neither FBs nor filopodia were observed. An important feature of T. similis spermatozoa is the late formation of MO; they first appear in mature spermatozoa. This pattern of MO formation is known for several other orders of the nematode class Enoplea: Enoplida, Mermithida, Dioctophymatida, Trichinellida but has never been observed in the class Chromadorea.     

Effect of unilateral extraction of molar teeth on suprahyoid muscles: macroscopic and ultrastructural aspects

Anatomical and physiologic components are parts of the stomatognathic system and their interaction results in integrated functional activities. Important alterations in the masticatory system originated by dental loss affect the bone, oral mucosa and muscular function. Dental arch structures specifically designed to receive and expose teeth allow performance of their functions. But the distinction between bony and soft tissues is lost when teeth are removed since there is not a specific function to be completed. The aim of this study was to evaluate the macroscopic and ultrastructural effects of the unilateral extraction of molar teeth on the suprahyoid muscles function, using twenty young male gerbils (Meriones unguiculatus) as the experimental animal model. They were divided in experimental malocclusion (n=10) and control (n=10) groups. The experimental malocclusion group was submitted to exodontia of the left upper molars and the control group was not submitted to this procedure and served as sham-operated. For macroscopic analysis of the suprahyoid muscle, the skin was uplifted and the muscles dissected individually and removed for weight analysis according to Scherle method. The electron microscopy analysis was made in ultra thin sections of small suprahyoid muscle fragments from the experimental and control groups, examined in a Jeol 1010, 880Kv transmission electron microscope. Several micrographs at magnifications of 3000x, 6000x, 30,000x were randomly selected for the qualitative analysis of the muscle fiber ultrastructures. Sixty days after the induced unilateral occlusal alteration no macroscopic morphologic changes was detected in the suprahyoid muscles and the muscle volume differences between the right and left sides and between groups were not significant. However, in the ultrastructural analysis suprahyoid muscles showed characteristics of specific adaptation to the unilateral occlusal alteration, by the reduced density of subsarcolemmal mitochondria and the shorter and less numerous ramifications in intermyofibrilar mitochondria localized between electronlucid myofibrils. It is concluded that unilateral exodontia of all the upper left molars affect the ultrastructural morphology of suprahyoid muscle fibers.     

Metal–Polymer Hybrid Nanoparticles for Correlative High‐Resolution Light and Electron Microscopy

The combination of fluorescence microscopy and electron microscopy promises a deeper insight into the ultrastructural features of cell organelles, e.g., after drug administration. Both methods complement each other and provide, as a correlative approach, a keen insight into the fate of nanoparticles within the cell. Moreover, it represents a promising tool to determine alterations of the cellular environment as a response to particle uptake. However, the availability of suitable correlative markers is mandatory for such correlative approaches. In this contribution, the utilization of poly(ethylene imine) based metal–polymer hybrid particles labeled with small gold nanoparticles and Rhodamine B facilitating the observation of the particles by means of fluorescence as well as by transmission electron microscopy is suggested. Correlative light and electron microscopy is used to study uptake and intracellular fusion processes of endosomal/lysosomal structures.     

Altered state of primordial follicles in neonatal and early infantile rats due to maternal hypothyroidism: Light and electron microscopy approach

Thyroid hormones (TH) are one of the key factors for normal prenatal development in mammals. Previously, we showed that subclinical maternal hypothyroidism leads to premature atresia of ovarian follicles in female rat offspring in the pre-pubertal and pubertal periods. The influence of decreased concentration of TH on primordial follicles pool formation during neonatal and early infantile period of rat pups was not investigated previously. Maternal hypothyroidism during pregnancy has irreversible negative influence on primordial follicles pool formation and population of resting oocytes in female rat offspring. The study was done on neonatal and early infantile control (n-10) and hypothyroid (n-10) female rat pups derived from control (n-6) and propylthiouracil (PTU) treated pregnant dams (n-6), respectively. Ovaries of all pups were removed and processed for light and transmission electron microscopy (TEM). Number of nests, oogonia and oocytes per nest, primordial, primary, secondary and preantral follicles were determined. Screening for overall calcium presence in ovarian tissue was done using Alizarin red staining. Morphology and volume density of nucleus, mitochondria and smooth endoplasmic reticulum (sER) in the oocytes in primordial follicles was also assessed. Caspase-3 and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), both markers for apoptosis, and proliferating cell nuclear antigen (PCNA) for proliferation were determined in oocytes and granulosa cells in different type of follicles. In neonatal period, ovaries of hypothyroid pups had a decreased number of oogonia, oocytes and nests, an increased number of primordial follicles and a decreased number of primary and secondary follicles, while in early infantile period, increased number of primary, secondary and preantral follicles were found. Alizarin red staining was intense in hypothyroid neonatal rats that also had the highest content of dilated sER. Number of mitochondria with altered morphology in both groups of hypothyroid pups was increased. Apoptosis markers have not shown significant difference between groups but PCNA had an increased expression in the oocytes and granulosa cells in primordial follicles of hypothyroid rats. Light and electron microscopy analysis indicate that previously detected premature ovarian follicular atresia in pre-pubertal and pubertal hypothyroid rats is preceded with premature formation of primordial follicles followed by slight changes on sER and mitochondria in examined oocytes, and increased expression of PCNA.     

Ultrastructure of the siphonaceous green alga Halimeda cuneata,with emphasis on the cytoskeleton

Cytoplasm streaming is a fundamental process for the transport of molecules and organelles in plant cells. In vegetative filaments of the coenocytic green alga, Halimeda cuneata Hering, the spatial organisation of microtubules in the cytoplasmic layer, was observed under transmission electron microscopy. A cross section of a cortical filament shows a tubular cell wall enclosing a peripheral layer of cytoplasm with numerous chloroplasts, amyloplasts, nuclei, mitochondria and microtubules surrounding a small central vacuole. Towards the thallus medulla the central vacuole enlarges considerably and the cytoplasm becomes gradually reduced to a thin parietal layer, the number of organelles is reduced and the quantity of microtubules increases. Therefore, most of the thallus volume is occupied by the huge central vacuole which extends throughout the coenocytic filaments. Microtubules run longitudinally, being about 0.05 μm from each other. Some microtubules were observed in close association to cell organelles.     

Ultrastructure of Gentiana tibetica proembryogenic cells before and after cooling treatments

The influence of increased concentrations of sucrose, 0.4 M sorbitol, DMSO and vitrification solution (PVS2) on the ultrastructure of non-frozen and frozen suspensions of Gentiana tibetica King ex Hook. F.tissue cells was investigated. Embryogenic aggregates were composed of three groups of cells of different size with various types of plastids. The ultrastructural changes resulting from increasing the sucrose concentration in the medium from 3 to 6 percent for 4 weeks and from treatment with 0.4 M sorbitol for 48 h were similar. Observations showed replacement of large vacuoles by numerous small ones, condensation of cytoplasm, accumulation of starch, and fragmentation of endoplasmic reticulum. Treatment with PVS2 led to degradation of starch, coalescence of amyloplasts and to shrinking of nucleoli from the third group of cells when originating from 6 percent sucrose medium. The mitochondria initially had various shapes, but after PVS2 treatment showed only spherical shapes with sparse cristae. After programmed freezing of tissue protected by sorbitol and DMSO, lethal damage was observed: membrane and nuclei degradation, and cell destruction. Reversible changes after freezing were observed in tissue pretreated with vitrification solution: dilation of cell membranes, mitochondria with electron-lucent vessels, aggregation of numerous vesicles, and degradation of starch in amyloplasts. In cells cooled by a vitrification method, cell organelles appeared normal as early as 5 h after thawing, and anomalies were not observed after 48 h of post-thawing culture.     

Differential distribution of some extracellular matrix fibers in an experimentally denervated rat megaileum

Absence of enteric neurons is associated with thickening of the intestinal muscularis externa in Chagas' disease. The thickening is due to hyperplasia and hypertrophy of the smooth muscle cells and increased extracellular matrix components. The influence of the nervous system on the structure of the smooth muscle cells and its associated matrix has been poorly investigated. An experimental model of denervation of the ileum in rats was performed by application of the surfactant agent benzalkonium chloride that selectively destroys the myenteric plexus. Three months later, ileal tissue samples were obtained and studied by histochemistry and transmission electron microsocopy. Sham operated rats were used as controls. The diameter of collagen fibrils was evaluated in electron micrographs. The histopathological analysis showed thickening of the muscular layer. The thin and weakly arranged collagen and reticulin fibers surrounding the smooth muscle cells, observed in control cases by Picrosirius polarization (PSP) stain method, corresponded to a population of loosely packed thin collagen fibrils of uniform diameters (mean=29.16 nm) at the ultrastructural level. In contrast, the thick and strongly birefringent fibers around the muscle cells, observed in the treated group, stained by PSP, corresponded to densely packed thicker fibrils with large variation in diameter (mean=39.41 nm). Comparison of the data demonstrated statistically significant difference between the groups suggesting that the replacement of loosely arranged reticulin fibers by fibrous tissue (with typical collagen fiber), may alter the biomechanical function resulting in impairment of muscular contraction.     

Ultrastructural alterations in the ventricular myocardium of the adult Italian newt (Lissotriton italicus) following exposure to nonylphenol ethoxylate

Nonylphenols ethoxylates (NPEs) are surface active agents (surfactants) commonly used in cleaning products, in industrial processes, agricultural formulations and paints. They are found in sewage, municipal wastewaters and industrial effluents, and as contaminants in water bodies. Accumulating data suggest that exposure to NPEs can adversely affects functional properties of the neurologic, reproductive, immune, and endocrine systems. In order to examine whether NPEs exert similar damaging effects on the cardiovascular system, we used an amphibian model to examine the ultrastructural alterations of the ventricular myocardium following exposure to NPEs. Adult Lissotriton italicus in the aquatic phase were exposed to NPE10 (100 μg/L, ppb) for 96 h. Heart specimens were collected from a total of 10 individuals and processed for scanning and transmission electron microscopy. Our ultrastructural examinations demonstrated that amphibian ventricle is susceptible to the effects of NPEs. The most pronounced alterations were observed in the membrane compartments of both myocardial and endothelial cells as demonstrated by the presence of swollen mitochondria with disrupted cristae and dilated rough endoplasmic reticulum. We suggest that destabilization of the lipid milieu within membranes might represent one of the potential mechanisms by which NPEs exert their toxic effects on amphibian heart.     

Novel organelles in primate retinal epithelium

We are investigating age-related changes in organelles in monkey retinal epithelium using transmission and analytic electron microscopy. We previously described a circular organelle in retinal epithelium with a diameter of about 0.5 μm. The organelle is unique in containing a single, round vacuole within an otherwise electron dense interior. We suggested that the organelle might be a melanosome with lysosomal properties. We now find that there are two similar organelles with such a single vacuole but which differ in their chemical composition, electron density, cell location and according to age.Epon embedded sections from the macular epithelium of seven monkeys, ranging from 1 to 35 years of age, were examined by transmission electron microscopy. A seven year old monkey was processed for analytic electron microscopy to determine the chemical composition of the organelles. The number and location of the organelles in the retinal epithelium were determined.The chemical composition of these two organelles was different. One of the organelles contained high mole fractions of oxygen and nitrogen and little phosphorous characteristic of melanin; the other had little oxygen and nitrogen and higher mole fractions of phosphorous uncharacteristic of melanin, but more common with lysosomal organelles. The latter had an electron dense rim around the vacuole, a less electron dense interior than the melanin containing organelle and also contained iron. The melanin containing organelle was more common in young monkeys and in the middle third of the cell. The organelle without melanin was more common in old monkeys and localized in the basal third of the cell.Two similarly vacuolated organelles, not identified before in retinal epithelium, differ in their chemical composition. One contains melanin; the other does not. The former is more common in young and the latter more common in old monkeys. This suggests reorganization and or degradation of melanin-containing organelles with age. These changes show how analytic electron microscopy can distinguish major ultra-structural differences in organelles when mere observation fails to do so easily.