Imperative role of electron microscopy in toxicity assessment: A review

Electron microscope (EM) was developed in 1931 and since then microscopical examination of both the biological and non-biological samples has been revolutionized. Modifications in electron microscopy techniques, such as scanning EM and transmission EM, have widened their applicability in the various sectors such as understanding of drug toxicity, development of mechanism, criminal site investigation, and characterization of the nano-molecule. The present review summarizes its role in important aspects such as toxicity assessment and disease diagnosis in special reference to SARS-COV2. In the biological system, EM studies have elucidated the impact of toxicants at the ultra-structural level in various tissue in conformity to physiological alterations. Thus, EM can be concluded as an important tool in toxicity assessment and disease prognosis.     

Immunolocalization of corneous proteins including a serine‐tyrosine‐rich beta‐protein in the adhesive pads in the tokay gecko

Adhesive pads of geckos contain many thousands of nanoscale spatulae for the adhesion and movement along vertical or inverted surfaces. Setae are composed of interlaced corneous bundles made of small cysteine‐glycine‐rich corneous beta proteins (CBPs, formerly indicated as beta‐keratins), embedded in a matrix material composed of cytoskeletal proteins and lipids. Negatively charged intermediate filament keratins (IFKs) and positively charged CBPs likely interact within setae, aside disulphide bonds, giving rise to a flexible and resistant corneous material. Using differernt antibodies against CBPs and IFKs an updated model of the composition of setae and spatulae is presented. Immunofluorescence and ultrastructural immunogold labeling reveal that one type of neutral serine‐tyrosine‐rich CBP is weakly localized in the setae while it is absent from the spatula. This uncharged protein is mainly present in the thin Oberhautchen layer sustaining the setae, although with a much lower intensity with respect to the cysteine‐rich CBPs. These proteins in the spatula likely originate a positively charged or neutral contact surface with the substrate but the influence of lipids and cytoskeletal proteins present in setae on the mechanism of adhesion is not known. In the spatula, protein‐lipid complexes may impart the pliability for the attachment and adapt to irregular surfaces. The presence of cysteine‐glycine medium rich CBPs and softer IFKs in alpha‐layers sustaining the setae forms a flexible base for compliance of the setae to substrate and improved adhesion.     

Effect of cooking temperature on texture and flavour binding of braised sauce porcine skin

To investigate the effect of cooking temperature (55, 65, 75, 85 and 95 °C) on texture and flavour binding of braised sauce porcine skin (BSPS), sensory acceptance, microstructure and flavour-binding capacity were investigated during the processing of BSPS. Samples cooked at 85 and 95 °C showed better texture and aroma scores. Hardness and chewiness of BSPS were obviously improved at 85 and 95 °C than control group. Collagen structure was significantly destroyed over 85 °C. The porcine skin collagen heated at 85 and 95 °C showed relatively higher flavour-binding capacity than other samples. The improvement of texture of BSPS was mainly attributed to the degradation of collagen. Higher aroma scores of BSPS were related to intense binding abilities with aroma compounds at 85 and 95 °C. Cooking at 85 or 95 °C could be an optimal cooking temperature for BSPS.     

Ontogeny of the testicular excurrent duct system of male Japanese quail (Coturnix japonica): A histological,ultrastructural, and histometric study

The testicular excurrent duct system undergoes several physiological and morphological changes during the reproductive stage or breeding season in mammals, birds, and reptiles. Studies on normal age-related histomorphological changes in the excurrent duct system of Japanese quails (Coturnix japonica) remain unreported, despite the extensive use of this bird as an avian model in research studies. The current study investigated the histological, ultrastructural, and histometric changes in the testicular excurrent duct system of the Japanese quail during three reproductive stages, namely prepubertal, pubertal, and adult. Simple squamous to low cuboidal cells formed the epithelia of the rete testis in prepubertal and pubertal birds, while in adult birds the lining was low cuboidal to cuboidal. In pubertal and adult birds, the nonciliated Type I epithelial cells of the proximal efferent duct displayed a subapical endocytotic apparatus comprising coated pits, coated apical tubules, and endosomes. There was a significant increase (p ≤ .001) in epithelial heights of all ducts of the excurrent duct system in the mature, sexually active, adult birds when compared to the other age groups. The luminal and tubular diameters, and the cross-sectional areas of efferent ducts and the epididymal duct unit increased significantly (p ≤ .001) with age. It is concluded that the morphology and morphometry of the excurrent ducts of the testis of the Japanese quail change as birds mature.     

Long-Term Spinal Ventral Root Reimplantation,but not Bone Marrow Mononuclear Cell Treatment,Positively Influences Ultrastructural Synapse Recovery and Motor Axonal Regrowth

We recently proposed a new surgical approach to treat ventral root avulsion, resulting in motoneuron protection. The present work combined such a surgical approach with bone marrow mononuclear cells (MC) therapy. Therefore, MC were added to the site of reimplantation. Female Lewis rats (seven weeks old) were subjected to unilateral ventral root avulsion (VRA) at L4, L5 and L6 levels and divided into the following groups (n = 5 for each group): Avulsion, sealant reimplanted roots and sealant reimplanted roots plus MC. After four weeks and 12 weeks post-surgery, the lumbar intumescences were processed by transmission electron microscopy, to analyze synaptic inputs to the repaired α motoneurons. Also, the ipsi and contralateral sciatic nerves were processed for axon counting and morphometry. The ultrastructural results indicated a significant preservation of inhibitory pre-synaptic boutons in the groups repaired with sealant alone and associated with MC therapy. Moreover, the average number of axons was higher in treated groups when compared to avulsion only. Complementary to the fiber counting, the morphometric analysis of axonal diameter and “g” ratio demonstrated that root reimplantation improved the motor component recovery. In conclusion, the data herein demonstrate that root reimplantation at the lesion site may be considered a therapeutic approach, following proximal lesions in the interface of central nervous system (CNS) and peripheral nervous system (PNS), and that MC therapy does not further improve the regenerative recovery, up to 12 weeks post lesion.     

The Effect of µ/m‐Calpain on Protein Degradation of Chicken Breast Meat

This study was designed to determine the effects of µ/m‐calpain on the degradation of cytoskeletal proteins in pectoralis major. Four chickens were slaughtered and the breasts were removed and stored for 12 hr at 4 °C. Each sample was divided into three groups and respectively immersed in control reagent, calpain inhibitor, and caspase inhibitor at 4 °C. The samples were used to evaluate troponin‐T and desmin degradation, calpain activity, and myofibril ultrastructure at 12 hr, day 1, day 3, and day 7. Casein zymography revealed that µ‐calpain could not be detected in all samples after 12 hr postmortem. The calpain inhibitor inhibited µ/m‐calpain activity and reduced troponin‐T and desmin degradation during 7 day postmortem. The caspase inhibitor inhibited µ/m‐calpain activity and, troponin‐T and desmin degradation before day 3 postmortem. The findings suggest that, µ/m‐calpain had an effect on cytoskeletal protein degradation after 12 hr postmortem.     

Inhibitory of multiple antifungal components produced by Lactobacillus plantarum K35 on growth,aflatoxin production and ultrastructure alterations of Aspergillus flavus and Aspergillus parasiticus

The antifungal activity of Lactobacillus plantarum K35 isolated from traditional Thai fermented rice noodle was evaluated against the growth and aflatoxin production of Aspergillus flavus TISTR304 and Aspergillus parasiticus TISTR3276. Multiple antifungal compounds secreted by L. plantarum were firstly analyzed using GC–MS in parallel to the ultrastructure alteration of the treated fungi. L. plantarum K35 supernatant caused significant reduction of the fungal growth and aflatoxin production. The antifungal activity was pH-dependent and favorable to acidic conditions whereas the catalase treatment had no influence indicating no involvement of hydrogen peroxide in the inhibition. Antifungal substances were resistant to sterilization and proteolytic enzymes including trypsin and proteinase K. The major components, apart from lactic acid, were 2-butyl-4-hexyloctahydro-1H-indene (19.55%), oleic acid (10.52%) and palmitic acid (7.27%). Other minor antifungal compounds included linoleic acid (2.11%), 2,4-di-tert-butylphenol (1.84%), stearic acid (1.55%), 3-phenyllactic acid (1.42%) and pyroglutamic acid (1.07%). The morphological changes of the fungi exposed to the supernatant were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). L. plantarum K35 supernatant caused severe damage to the cell wall and cytoplasmic membrane leading to a massive loss of cytoplasmic content, the formation of membrane-bound vesicles, and complete destruction of membranous organelles including mitochondria and nucleus.     

刺五加雌、雄花的花柱引导组织结构观察

利用光学显微镜、透射电子显微镜观察了刺五加(Eleutherococcus senticosus)雌、雄花的花柱及其引导组织的结构。结果表明:1.刺五加花柱处合生心皮内表面未完全融合,形成由中心向四周分支的裂缝;2.雌性花柱较雄性花柱,引导组织更为发达;3.发育过程中引导组织细胞内不断有储存为脂体的营养物质分解,并分泌到细胞间隙;4.传粉后,雌花花柱引导组织的部分细胞发生降解,形成大的溶生的细胞间隙,花粉管从中穿过,而雄花花柱中未见溶生的细胞间隙,亦未见花粉管穿过。