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Growth associated protein 43 and neurofilament immunolabeling in the transected lumbar spinal cord of lizard indicates limited axonal regeneration

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Neural Regeneration Research 2022年第5期17卷 1034-1041页

作者： lorenzo alibardi Comparative Histolab Padova and Department of Biology University of BolognaBolognaItaly

Previous cytological studies on the transected lumbar spinal cord of lizards have shown the presence of differentiating glial cells,few neurons and axons in the bridge region between the proximal and distal stumps of the spinal cord in some cases.A limited number of axons(20-50)can cross the bridge and re-connect the caudal stump of the spinal cord with small neurons located in the rostral stump of the spinal cord.This axonal regeneration appears to be related to the recovery of hind-limb movements after initial paralysis.The present study extends previous studies and shows that after transection of the lumbar spinal cord in lizards,a glial-connective tissue bridge that reconnects the rostral and caudal stumps of the interrupted spinal cord is formed at 11-34 days post-injury.Following an initial paralysis some recovery of hindlimb movements occurs within 1-3 months post-injury.Immunohistochemical and ultrastructural analysis for a growth associated protein 43(GAP-43)of 48-50 k Da shows that sparse GAP-43 positive axons are present in the proximal stump of the spinal cord but their number decreased in the bridge at 11-34 days post-transection.Few immunolabeled axons with a neurofilament protein of 200-220 k Da were seen in the bridge at 11-22 days post-transection but their number increased at 34 days and 3 months post-amputation in lizards that have recovered some hindlimb movements.Numerous neurons in the rostral and caudal stumps of the spinal cord were also labeled for GAP43,a cytoplasmic protein that is trans-located into their axonal growth cones.This indicates that GAP-43 biosynthesis is related to axonal regeneration and sprouting from neurons that were damaged by the transection.Taken together,previous studies that utilized tract-tracing technique to label the present observations confirm that a limited axonal re-connection of the transected spinal cord occurs 1-3 months post-injury in lizards.The few regenerating-sprouting axons within the bridge reconnect the caudal with the rostral stumps of the spina

关键词： GAP-43 immunocytochemistry lizard neurofilaments regeneration spinal cord

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Immunodetection of ephrin receptors in the regenerating tail of the lizard Podarcis muralis suggests stimulation of differentiation and muscle segmentation

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Zoological Research 2019年第5期40卷 416-426页

作者： lorenzo alibardi Comparative Histolab Padova and Department of Biology University of Bologna

Ephrin receptors are the most common tyrosine kinase effectors operating during development. Ephrin receptor genes are reported to be up-regulated in the regenerating tail of the Podarcis muralis lizard. Thus, in the current study, we investigated immunolocalization of ephrin receptors in the Podarcis muralis tail during regeneration. Weak immunolabelled bands for ephrin receptors were detected at 15–17 kDa, with a stronger band also detected at 60–65 kDa. Labelled cells and nuclei were seen in the basal layer of the apical wound epidermis and ependyma, two key tissues stimulating tail regeneration. Strong nuclear and cytoplasmic labelling were present in the segmental muscles of the regenerating tail, sparse blood vessels, and perichondrium of regenerating cartilage. The immunolocalization of ephrin receptors in muscle that gives rise to large portions of new tail tissue was correlated with their segmentation. This study suggests that the high localization of ephrin receptors in differentiating epidermis, ependyma, muscle, and cartilaginous cells is connected to the regulation of cell proliferation through the activation of programs for cell differentiation in the proximal regions of the regenerating tail. The lower immunolabelling of ephrin receptors in the apical blastema, where signaling proteins stimulating cell proliferation are instead present, helps maintain the continuous growth of this region.

关键词： Lizard Regenerating blastema Ephrin receptors Immunolabelling Western blotting

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Tail regeneration reduction in lizards after repetitive amputation or cauterization reflects an increase of immune cells in blastemas

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Zoological Research 2018年第6期39卷 413-423页

作者： lorenzo alibardi Comparative Histolab Padua Department of BiologyUniversity of Bologna

Lizards are key amniote models for studying organ regeneration. During tail regeneration in lizards, blastemas contain sparse granulocytes, macrophages, and lymphocytes among the prevalent mesenchymal cells. Using transmission electron microscopy to examine scarring blastemas after third and fourth sequential tail amputations, the number of granulocytes, macrophages, and lymphocytes increased at 3-4 weeks in comparison to the first regeneration. An increase in granulocytes and agranulocytes also occurred within a week after blastema cauterization during the process of scarring Blood at the third and fourth regeneration also showed a significant increase in white blood cells compared with that under normal conditions and at the first regeneration. The extracellular matrix of the scarring blastema, especially after cauterization, was denser than that in the normal blastema and numerous white blood cells and fibroblasts were surrounded by electron-pale, fine fibrinoid material mixed with variable collagen fibrils. In addition to previous studies, the present observations support the hypothesis that an increase in inflammation and immune reactions determine scarring rather than regeneration. These new findings verify that an immune reaction against mesenchymal and epidermal cells of the regenerative blastema is one of the main causes for the failure of organ regeneration in amniotes.

关键词： Lizard Tail Repetitive regeneration Blood Immune cells Ultrastructure

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Regeneration of adhesive tail pad scales in the New Zealand gecko (Hoplodactylus maculatus) (Reptilia, Squamata; Lacertilia) can serve as an experimental model to analyze setal formation in lizards generally

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Zoological Research 2017年第4期38卷 191-197页

作者： lorenzo alibardi Benno Meyer-Rochow Comparative Histolab and Department of Bigea Dipartimento di Biologia University of Bologna Bologna 40126 Italy Research Institute of Luminous Organisms Tokyo 100-1623 Japan Department of Genetics and Physiology Oulu University Oulu FIN 90140 Finland

During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation of these specialized scales from epidermal pegs that invaginate the dermis of the regenerating tail are described on the basis of light and electron microscopic images. Within the pegs a differentiating clear layer interfaces with the spinulae and setae of the Oberh^utchen according to a process similar to that described for the digital pads. A layer of clear cytoplasm surrounds the growing tiny setae and eventually comities around them and their spatular ends, later leaving the new setae free- standing on the epidermal surface. The fresh adhesive pads help the gecko to maintain the prehensile function of its regenerated tail as together with the axial skeleton （made of a cylinder of elastic cartilage） the pads allow the regenerated tail to curl around twigs and small branches just like the original tail. The regeneration of caudal adhesive pads represents an ideal system to study the cellular processes that determine setal formation under normal or experimental manipulation as the progressive phases of the formation of the setae can be sequentially analyzed.

关键词： Gecko lizard Regeneration Epidermis Tail pad scales Adhesion Prehensile function Ultrastructure

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Ultrastructural analysis shows persistence of adhesion and tight junction proteins in mature human hair

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BIOCELL 2021年第4期45卷 1013-1022页

作者： lorenzo alibardi BERND NOECKER Comparative Histolab Padova and Department of Biology University of BolognaBologna40126Italy KAO Europe Research Laboratories Kao Germany GmbHDarmstadt64297Germany

The differentiation of cells composing mature human hairs produces layers with different corneous characteristics that would tend to flake away one from another,as in the corneous layer of the epidermis,without anchoring junctions.It is likely that cell junctions established in the forming cells of the hair bulb are not completely degraded like in the corneous layer of the epidermis but instead remain in the hair shaft to bind mature cuticle,cortex,and medulla cells into a compact hair shaft.During cell differentiation in hairs,cell junctions seem to disappear,and little is known about the fate of junctional proteins present in the mature human hair shaft.The present ultrastructural immunogold study has detected some marker proteins of adhesion junction(cadherin and beta-catenin)and tight junctions(occludin and cingulin)that are still present in cornified hairs where numerous isopeptide bonds are detected,especially in the medulla.This qualitative ultrastructural study indicates that aside from the cell membrane complex,a long corneo-desmosome bonding cortex and cuticle cells,also sparse adherens and tight junction remnants are present.It is suggested that the cornification of these junctions with the incorporation of their proteins within the mature corneous material of the hair shaft likely contributes to maintaining the integrity of the mature hair.This information will also allow us to evaluate the effects of different chemical components present in hair formulations and stains on these junctional proteins and the consequent integrity of the hair shaft.

关键词： Human hair Cornification Adhesion junctions Tight junctions Immunogold Ultrastructure

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白边油蝠表皮角质化细胞末端分化的超微结构(英文)

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Zoological Research 2006年第1期27卷 86-93页

作者： lorenzo alibardi 意大利博洛尼亚大学生物进化实验系

蝙蝠是一种唯一能够飞行的哺乳动物，其皮肤的超微结构尚未见报道。在电镜下观察了白边油蝠（Pipistrellus kuhlii）背部和翼膜皮肤的超微结构。表皮的厚度较低（10～12μm），角质层下有1～2层的刺细胞，该刺细胞由相似于鸟类无羽表皮... 详细信息

蝙蝠是一种唯一能够飞行的哺乳动物，其皮肤的超微结构尚未见报道。在电镜下观察了白边油蝠（Pipistrellus kuhlii）背部和翼膜皮肤的超微结构。表皮的厚度较低（10～12μm），角质层下有1～2层的刺细胞，该刺细胞由相似于鸟类无羽表皮的纤细角化细胞形成。颗粒层不连续且仅有少量小型透明角质颗粒（〈0．3μm）。在翼膜的若干区域，表皮简化为一层与角质层相连的基底层。过渡期的角化细胞几乎不存在，提示其角质化过程非常迅速。基底膜上的无数半桥粒在真皮下面形成密集的附着点。大量胶原纤维直接维系在半桥粒和基底膜的致密层上，稀疏的弹性纤维使得蝙蝠表皮在飞行时易于伸展、在飞行后易于迅速折叠而不会受到损伤。与鸟类的表皮相似，蝙蝠角化细胞富有大量的脂质。由于脂质有助于蝙蝠皮肤在飞行中与冷空气流的传热绝缘。大量脂质的存在可能是为补偿蝙蝠翼膜的真皮缺乏厚的脂肪层。研究还表明，毛发较薄（4～7μm），并具有与皮层相似的突状物组成的精细表皮，其表皮细胞形成钩状抓握点使毛发紧紧粘结在一起，通过这种方式毛皮保持紧凑以恒定体温。

关键词：蝙蝠皮肤表皮毛发角质化超微结构

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