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PubMed1995

Enhancement of nuclear Ca(2+)-ATPase activity in regenerating rat liver: involvement of nuclear DNA increase.

The alteration of calcium content, Ca(2+)-ATPase activity, DNA content and DNA fragmentation in the nuclei of regenerating rat liver was investigated. Liver was surgically removed about 70% of that of sham-operated rats. The reduced liver weight by partial hepatectomy was completely restored at 3 days after the surgery. Regenerating liver significantly increased Ca(2+)-ATPase activity and DNA content in the nuclei between 1 and 5 days after hepatectomy. The nuclear calcium content was clearly increased from 2 days after hepatectomy. The increase of Ca(2+)-ATPase activity in regenerating liver was clearly inhibited by the presence of trifluoperazine (10 microM), staurosporine (2.5 microM) and dibucaine (10 microM), which are inhibitors of calmodulin and protein kinase, in the enzyme reaction mixture. However, the nuclear enzyme activity in normal rat liver was not significantly altered by these inhibitors. Meanwhile, the increase of nuclear DNA content in regenerating liver was completely blocked by the administration of trifluoperazine (2.5 mg/100 g body weight), suggesting an involvement of calmodulin. Now, the nuclear DNA fragmentation was significantly decreased in regenerating liver, suggesting that this decrease is partly contributed to the increase in nuclear DNA content. The present study clearly demonstrates that regenerating liver enhances nuclear Ca(2+)-ATPase activity and induces a corresponding elevation of nuclear calcium content. This Ca(2+)-signaling system may be involved in the regulation of nuclear DNA functions in regenerating rat liver.

Alkaloids↗
PubMed1983

Myelination of regenerating sciatic nerve of the rat: lipid components and synthesis of myelin lipids.

Changes of lipid, free fatty acid, protein, DNA, and RNA content in proximal and distal segments of regenerating sciatic nerve, from 14 to 120 days after crush, were determined. During the early stage of Wallerian degeneration, a marked decrease of phospholipid, cerebroside and sulfatide content and, in contrast, a marked increase of protein, DNA, RNA, and free fatty acid content, in the distal segment of crushed nerve compared to control, was observed. A gradual increase of phospholipid, cerebroside, and sulfatide levels, approaching normal values, and a gradual slope in the increase of protein, DNA, RNA, and free fatty acid levels over the ensuing time periods of regeneration was seen. Total cholesterol content was relatively constant during regeneration, slightly increasing at day 120. The activity of 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) of myelin fraction purified from distal segment of regenerating sciatic nerve showed a significant increase in the 30-120 day regenerating period. A marked increase of the incorporation of [2-3H]glycerol and of [Me-14C]choline into myelin lipids of distal segment of regenerating nerve, was found. Labeling of myelin lipids with [3H]oleic acid (injected intravenously seven days before crush) support the evidence that a similar pattern of degeneration exists between two different types of trauma, i.e. nerve crush or cut. The findings suggest that, in the distal segment of crushed nerve, the lipid content as well as the myelin lipid synthesis increase as the regeneration period proceeds.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1987

Molecular forms and localization of acetylcholinesterase and nonspecific cholinesterase in regenerating skeletal muscles.

Molecular forms and histochemical localization of acetylcholinesterase and nonspecific cholinesterase were analysed in muscle regenerates obtained from rat EDL and soleus muscles after ischaemic-toxic degeneration and irreversible inhibition of preexistent enzymes. Regenerating myotubes and myofibres produce the 16S AChE form in the absence of innervation. The 10S AChE form prevails over 4S form with maturation into striated fibres. Although the patterns of AChE molecular forms in normal EDL and soleus muscles differ significantly no such differences were observed in noninnervated regenerates from both muscles. Two types of focal accumulation of AChE appear on the sarcolemma of regenerating muscles: first, in places of former motor endplates and, second, in extra-junctional regions. The 4S form of nonspecific cholinesterase is prevailing in regenerating myotubes whereas its asymmetric forms or focal accumulations could not be identified reliably. The satellite cells which survive after muscle degeneration probably originate from some type of late myoblasts and transmit the information concerning the ability to synthesize the asymmetric AChE forms and to focally accumulate AChE to regenerating muscle cells. Synaptic basal lamina from former motor endplates may locally induce AChE accumulations in regenerating muscles.

Acetylcholinesterase↗
PubMed1992

Temporal and spatial patterns of expression of laminin, chondroitin sulphate proteoglycan and HNK-1 immunoreactivity during regeneration in the goldfish optic nerve.

Current views suggest that the extracellular environment is critically important for successful axonal regeneration in the CNS. The goldfish optic nerve readily regenerates, indicating the presence of an environment that supports regeneration. An analysis of changes that occur during regeneration in this model may help identify those molecules that contribute to a favourable environment for axonal regrowth. We examined the distribution and expression of two extracellular matrix molecules, laminin and chondroitin sulphate proteoglycan, and a carbohydrate epitope shared by a family of adhesion molecules (HNK-1), using immunocytochemical detection in sections from the normal adult goldfish optic nerve and in nerves from one hour to five months following optic nerve crush. We also used in vitro preparations to determine if neurites in retinal explants could express these same molecules. The linear distributions of laminin and chondroitin sulphate proteoglycan immunoreactivity in control optic nerves are co-extensive with the glia limitans, suggesting both are expressed by non-neuronal components surrounding the axon fascicles. Between one and three weeks postoperatively when axons elongate and reach their target, laminin and chondroitin sulphate proteoglycan immunoreactivity increases around the crush site and distally. At six weeks postoperatively the pattern of immunoreactivity has returned to normal. While the temporal pattern of changes in immunoreactivity is similar, the spatial pattern of these two extracellular proteins in the regenerating nerve differs. Chondroitin sulphate proteoglycan immunoreactivity is organized in discrete columns associated with regenerating axons while laminin immunoreactivity is more diffusely distributed. Examination of retinal explants reveals growing neurites express chondroitin sulphate proteoglycan but not laminin. Our results suggest that laminin is only associated with non-neuronal cells, while chondroitin sulphate proteoglycan is associated with axons as well as non-neuronal cells. HNK-1 immunoreactivity is co-extensive with both the glia limitans and axon fascicles and is more extensively distributed in the intact nerve than either laminin or chondroitin sulphate proteoglycan immunoreactivity. In contrast to laminin and chondroitin sulphate proteoglycan, HNK-1 immunoreactivity is substantially decreased at the crush site within one week following optic nerve crush. HNK-1 immunoreactivity reappears through the crush site during the next several weeks, although non-immunoreactive regions, co-extensive with areas predominantly containing non-neuronal cells, persist both proximal and distal to the crush, up to six weeks postoperatively. The pattern suggests that HNK-1 epitope expression by these non-neuronal cells is decreased during axonal regeneration.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Regeneration of axons in the optic nerve of the adult Browman-Wyse (BW) mutant rat.

We have studied the regeneration of axons in the optic nerves of the BW rat in which both oligodendrocytes and CNS myelin are absent from a variable length of the proximal (retinal) end of the nerve. In the optic nerves of some of these animals, Schwann cells are present. Axons failed to regenerate in the exclusively astrocytic environment of the unmyelinated segment of BW optic nerves but readily regrew in the presence of Schwann cells even across the junctional zone and into the myelin debris filled distal segment. In the latter animals, the essential condition for regeneration was that the lesion was sited in a region of the nerve in which Schwann cells were resident. Regenerating fibres appeared to be sequestered within Schwann cell tubes although fibres traversed the neuropil intervening between the ends of discontinuous bundles of Schwann cell tubes, in both the proximal unmyelinated and myelin debris laden distal segments of the BW optic nerve. Regenerating axons never grew beyond the distal point of termination of the tubes. These observations demonstrate that central myelin is not an absolute requirement for regenerative failure, and that important contributing factors might include inhibition of astrocytes and/or absence of trophic factors. Regeneration presumably occurs in the BW optic nerve because trophic molecules are provided by resident Schwann cells, even in the presence of central myelin, oligodendrocytes and astrocytes. All the above experimental BW animals also have Schwann cells in their retinae which myelinate retinal ganglion cell axons in the fibre layer. Control animals comprised normal Long Evans Hooded rats, BW rats in which both retina and optic nerve were normal, and BW rats with Schwann cells in the retina but with normal, i.e. CNS myelinated, optic nerves. Regeneration was not observed in any of the control groups, demonstrating that, although the presence of Schwann cells in the retina may enhance the survival of retinal ganglion cells after crush, concomitant regrowth of axons cut in the optic nerve does not take place.

Animals↗
PubMed1988

Myogenic and neurogenic regulation of myosin gene expression in cat jaw-closing muscles regenerating in fast and slow limb muscle beds.

Immunocytochemical techniques were used to study changes in myosin gene expression during the regeneration of the cat posterior temporalis muscle transplanted into the bed of either the fast extensor digitorum longus (EDL) or the slow soleus muscle. Strips of the posterior temporalis, a homogeneously superfast muscle, were treated with Marcaine and then transplanted into limb muscle beds which had been completely cleared of host muscle fibres. The regenerates were examined 6 to 224 days after surgery. Early regenerates in both muscle beds reacted with antibodies against the heavy chain of foetal, slow and superfast myosins, but not with antibodies against fast myosin. In the long-term, regenerates innervated by the EDL nerve expressed only superfast myosin whereas in the regenerates innervated by the soleus nerve most fibres expressed only slow myosin and only a few fibres reacted exclusively with the anti-superfast myosin antibody even after 210 days. In contrast, EDL and soleus muscles regenerating in their own beds expressed foetal, slow and fast myosin, but did not express superfast myosin. The isometric contraction times of the various types of regenerates reflected the types of myosin synthesized. It is concluded that jaw and limb muscle cells exist as two distinct allotypes, each having a distinct repertoire for the expression of adult isomyosins, and that within that repertoire isomyosin gene expression can be modulated by the nerve. Thus, myosin gene expression in skeletal muscle fibres is regulated by both myogenic and neurogenic mechanisms.

Animals↗
PubMed1996

Peripheral nerve explants grafted into the vitreous body of the eye promote the regeneration of retinal ganglion cell axons severed in the optic nerve.

We have conducted experiments in the adult rat visual system to assess the relative importance of an absence of trophic factors versus the presence of putative growth inhibitory molecules for the failure of regeneration of CNS axons after injury. The experiments comprised three groups of animals in which all optic nerves were crushed intra-orbitally: an optic nerve crush group had a sham implant-operation on the eye; the other two groups had peripheral nerve tissue introduced into the vitreous body; in an acellular peripheral nerve group, a frozen/thawed teased sciatic nerve segment was grafted, and in a cellular peripheral nerve group, a predegenerate teased segment of sciatic nerve was implanted. The rats were left for 20 days and their optic nerves and retinae prepared for immunohistochemical examination of both the reaction to injury of axons and glia in the nerve and also the viability of Schwann cells in the grafts. Anterograde axon tracing with rhodamine-B provided unequivocal qualitative evidence of regeneration in each group, and retrograde HRP tracing gave a measure of the numbers of axons growing across the lesion by counting HRP filled retinal ganglion cells in retinal whole mounts after HRP injection into the optic nerve distal to the lesion. No fibres crossed the lesion in the optic nerve crush group and dense scar tissue was formed in the wound site. GAP-43-positive and rhodamine-B filled axons in the acellular peripheral nerve and cellular peripheral nerve groups traversed the lesion and grew distally. There were greater numbers of regenerating fibres in the cellular peripheral nerve compared to the acellular peripheral nerve group. In the former, 0.6-10% of the retinal ganglion cell population regenerated axons at least 3-4 mm into the distal segment. In both the acellular peripheral nerve and cellular peripheral nerve groups, no basal lamina was deposited in the wound. Thus, although astrocyte processes were stacked around the lesion edge, a glia limitans was not formed. These observations suggest that regenerating fibres may interfere with scarring. Viable Schwann cells were found in the vitreal grafts in the cellular peripheral nerve group only, supporting the proposition that Schwann cell derived trophic molecules secreted into the vitreous stimulated retinal ganglion cell axon growth in the severed optic nerve. The regenerative response of acellular peripheral nerve-transplanted animals was probably promoted by residual amounts of these molecules present in the transplants after freezing and thawing. In the optic nerves of all groups the astrocyte, microglia and macrophage reactions were similar. Moreover, oligodendrocytes and myelin debris were also uniformly distributed throughout all nerves. Our results suggest either that none of the above elements inhibit CNS regeneration after perineuronal neurotrophin delivery, or that the latter, in addition to mobilising and maintaining regeneration, also down regulates the expression of axonal growth cone-located receptors, which normally mediate growth arrest by engaging putative growth inhibitory molecules of the CNS neuropil.

Animals↗
PubMed1993

Natural killer cell may impair liver regeneration in fulminant hepatic failure.

The authors established a new experimental model of fulminant hepatic failure (FHF) with prolonged hepatocellular necrosis and impaired liver regeneration, and evaluated the immunological mechanisms related to the impaired liver regeneration in this model. A novel lipid A analogue, FS-112, was injected intravenously into male Balb/c mice, followed by a 70% partial hepatectomy 2 days later. Serum levels of T.Bil. and ALT rose 7 days after the partial hepatectomy, as compared with controls. In mice pretreated with FS-112, labeling indices of both BrdU and PCNA 36 hrs after the partial hepatectomy were significantly lower than those in the controls. Splenic lymphocytes harvested from the FHF mice 1-5 days after the partial hepatectomy showed a cytotoxic activity against regenerating hepatocytes with a peak effect on day 5. Cytotoxic activity against YAC-1 cells was also found up to 5 days after the partial hepatectomy, and resembled that directed against the regenerating hepatocytes. On the 5th day of FS-112 administration, there was a marked rise in the production of IFN-gamma from splenocytes. When FK-506, an immunosuppressive agent, was given intracutaneously daily for 7 days, serum levels of T.Bil. and ALT significantly decreased, as compared with controls. Furthermore, the PCNA-labeling index 36 hrs after the partial hepatectomy was enhanced by the administration with FK-506 in the FHF mice. These results strongly suggest that the NK cells activated by IFN-gamma may be involved in killing the regenerating liver cells, and thus play a role in the pathogenesis of the impaired liver regeneration in FHF.2+ recovery from the impaired liver regeneration in FHF.

Animals↗
PubMed1982

Regeneration of endocrine cells in the stomach.

A mucosal defect was produced by cryosurgery in the antral and the fundic wall of the rat stomach, and regeneration of gastric endocrine cells was studied 50, 100 and 200 days after operation. Fifty days after the operation, the mucosal defect was completely covered with regenerated epithelium. The regenerated mucosa both in the antral and in the fundic region consisted of mucinous glandular structures. The regenerated mucosa in the corpus remained pseudopyloric in type even 200 days after operation. Regardless of the time after operation, regeneration of endocrine cells was always observed. We could identify G cells and EC cells in the regenerated mucosa of the antrum, and EC cells, A cells and AL cells in the regenerated mucosa of the corpus, respectively. By electron microscopy, endocrine-exocrine cells were frequently encountered. These cells had two different types of intra-cytoplasmic granules; one was an endocrine-specific, small electron-dense granule, and the other a large, lucent mucin droplet-like granule. These findings indicate that the endocrine cells of the stomach are formed from endodermal precursor cells.

Animals↗
PubMed1991

The patterns of beta-cell regeneration in untreated diabetic and insulin-treated diabetic Syrian hamsters after streptozotocin treatment.

Our previous study showed that Syrian hamsters recover from streptozotocin (SZ)-induced diabetes spontaneously and that insulin therapy adversely affects diabetes. The recovery and lack of recovery was associated with beta-cell regeneration and lack of regeneration. In this study, we examined the patterns of beta-cell regeneration in hamsters by using an immunohistochemical-autoradiographical method. We used tritiated thymidine to examine the DNA synthesis in islet cells and evaluated the number of labeled cells that were or were not immunoreactive with antiinsulin, antiglucagon, and anatisomatostatin. The results showed that, in untreated control hamsters, beta-cell regeneration took place both from preexisting beta cells and from undifferentiated cells (labeled cells unstained with any of the three antibodies) in equal proportions. In the SZ-treated hamsters, however, most regenerating cells seemed to derive from undifferentiated cells within the islets. Insulin therapy inhibited beta-cell regeneration from both the preexisting cells, but more so from the undifferentiated cells. The number of extrainsular islet cell foci was the same in all treatment groups and paralleled the number of islets in each animal during the entire experiment. We concluded the following about diabetic hamsters: 1. beta-Cell regeneration occurs primarily from undifferentiated cells within the islet; 2. Exogenous insulin inhibits beta-cell differentiation from the precursor cells; and 3. The response of intrainsular and extrainsular islet cells to SZ and insulin therapy is similar and the number of extrainsular islet cell foci per pancreas parallel the changes in the number of islets.

Animals↗
PubMed2003

Role of metallothioneins in peripheral nerve function and regeneration.

The physiological role of the metallothionein (MT) family of proteins during peripheral nerve injury and regeneration was examined in Mt1+ 2 and Mt3 knockout (KO) mice. To this end, the right sciatic nerve was crushed, and the regeneration distance was evaluated by the pinch test 2-7 days postlesion (dpl) and electrophysiologically at 14 dpl. The quality of the regeneration was assessed by light microscopy and immunohistochemical methods. The results show that the regeneration distance was greater in the Mt3 KO than in the Mt1+ 2 KO mice, whereas control mice showed intermediate values. Moreover, the number of regenerating axons in the distal tibial nerve was significantly higher in Mt3KO mice than in the other two strains at 14 dpl. Immunoreactive profiles to protein gene product 9.5 were present in the epidermis and the sweat glands of the plantar skin of the hindpaw of the Mt3 KO group. The improved regeneration observed with the Mt3 KO mice was confirmed by compound nerve action potentials that were recorded from digital nerves at 14 dpl only in this group. We conclude that Mt3 normally inhibits peripheral nerve regeneration.

Animals↗
PubMed2003

Inheritance of plant regeneration from maize (Zea mays L.) shoot meristem cultures derived from germinated seeds and the identification of associated RAPD and SSR markers.

The inheritance of shoot regeneration through shoot-tip meristem culture derived from maize seedling was evaluated, and the markers (RAPD and SSR) associated with this regeneration character were identified both in a group of North American maize inbreds and a crossing population. A discrete distribution of percent regeneration and no. of shoots per explant was observed in the inbred group and the F(2) population. The results suggested that this regenerable trait was controlled by several major genes. Five RAPD markers were identified to be relevant to percent regeneration in maize shoot-tip culture system. One RAPD marker and three SSR markers were associated with no. of shoot per explant and its relevant traits. Of them marker BC603-1600 explained 18% of the variation for no. of shoot per explant and 16% of the variation for callus size. The BC603-1600 was sequenced and assigned in linkage group 7 based on a NCBI blast search. The information provided here should benefit to determine the genetic mechanisms involved in the maize regeneration response related to shoot meristem culture pathway and benefit to select high regenerable germplasm by using marker assisted selection.

Analysis of Variance↗
PubMed1999

Auxiliary liver transplantation: how to improve regeneration of the native liver by surgery.

The technical factors which could influence regeneration of the native liver (NL) in auxiliary liver transplantation (ALT) for fulminant hepatic failure (FHF) are not well known. We studied NL regeneration according to the location of graft anastomosis in the recipient's portal system (superior mesenteric vein versus portal vein), and graft weight (50% reduced-size versus full-size graft) in a rat model of ALT with 80% reduction of the NL, and graft arterialization. NL regeneration was significantly more obvious when the graft was anastomosed on the recipient's superior mesenteric vein, thus establishing venous flow to the NL from the pancreas, the spleen, and the stomach, and when a full-size graft was used. The influence of portal venous flow on NL regeneration, assessed by 3H[-thymidine incorporation, was measurable as early as day 2. Both technical variables in combination resulted in significantly greater regeneration (ratio weight of NL/body weight at day 30: 2.32 +/- 0.68% versus 1.21 +/- 0.63% respectively, P = 0.02). Early preservation of portal flow to the NL is advisable to maximize NL regeneration in ALT. In any case, this regeneration is not impeded by the use of large auxiliary grafts.

Animals↗
PubMed2002

Adventitious shoot regeneration from seven commercial strawberry cultivars (Fragaria x ananassa Duch.) using a range of explant types.

The parameters for optimal regeneration of seven commercial strawberry cultivars were tested using a range of explants and culture conditions. Efficient levels of regeneration--those needed to carry out transformation experiments--with the cultivars Calypso, Pegasus, Bolero, Tango and Emily were achieved with leaf discs, petioles, roots and stipules. Regeneration from cv. Elsanta proved to be difficult from all explant material, although unpollinated ovaries proved to be a promising explant source, with 12% of the explants regenerating shoots. In cv. Eros, regeneration occurred only from root tissue. A comparison of the genetic background suggests that there is a strong genetic component amongst the different cultivars determining their regeneration capacity. The development of these regeneration systems provides a means to use almost the whole stock plant for the efficient genetic transformation of commercial strawberry varieties.

Culture Techniques↗
PubMed2005

Efficient in vitro regeneration of fertile plants from corm explants of Hypoxis hemerocallidea landrace Gaza -- the "African Potato".

We present efficient protocols for the regeneration of fertile plants from corm explants of Hypoxis hemerocallidea Fisch. and C. A. Mey. landrace Gaza, either by direct multiple shoot formation or via shoot organogenesis from corm-derived calluses. The regeneration efficiency depended on plant growth regulator concentrations and combinations. Multiple direct shoot formation with high frequency (100% with 5-8 shoots/explant) was obtained on a basal medium (BM) supplemented with 3 mg/l kinetin (BM1). However, efficient indirect regeneration occurred when corm explants were first plated on callus induction medium (BM2) with high kinetin (3 mg/l) and naphthalene acetic acid (NAA 1 mg/l), and then transferred to shoot inducing medium (BM3) containing BA (1.5 mg/l) and NAA (0.5 mg/l). Shoot regeneration frequency was 100% and 30-35 shoots per explant were obtained. The regenerated shoots were rooted on a root inducing medium (BM4) containing NAA (0.1 mg/l). Rooted plantlets were transferred to the greenhouse. The regenerants were morphologically normal and fertile. Flow cytometric analyses and chloroplast counts of guard cells suggested that the regenerants were diploid. Efficient cloning protocols described here, have the potential not only to substantially reduce the pressure on natural populations but also for wider biotechnological applications of Hypoxis hemerocallidea-an endangered medicinal plant.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2004

Sequence of IGF-I, IGF-II, and HGF expression in regenerating skeletal muscle.

Various cytokines are thought to play a role in muscle regeneration, however, the interaction and mechanisms of action of these cytokines remains largely unknown. In this study, we investigated the role of HGF, IGF-I, and IGF-II during myogenesis using the regeneration model of skeletal muscle as well as myoblast culture. RT-PCR analysis revealed that HGF and IGF-I expressions were markedly upregulated, in regenerating muscle. In contrast, there was no significant difference in IGF-II expression between normal and regenerating muscle. Immunohistochemical analysis demonstrated that HGF was expressed mostly by myocytes during the early stages of muscle regeneration. Additionally, HGF inhibited the formation of myotubes by myoblasts, but promoted cellular proliferation. Otherwise, IGF-I and IGF-II were expressed by myocytes through the early to middle stages of muscle regeneration. The addition of HGF to myoblast growing in vitro significantly increased the number of cells. These findings indicate that these three cytokines have pleiotropic effects in regenerating skeletal muscle.

Animals↗
PubMed1997

Regulation of dihydropyridine receptor and ryanodine receptor gene expression in regenerating skeletal muscle.

One of the the major properties of mature skeletal muscle is its ability to regenerate after injury. The purpose of the present study was to determine whether the expression of genes encoding the dihydropyridine receptor calcium channel (DHPR) and the ryanodine receptor (RyR), which play a critical role in excitation-contraction coupling, is regulated by skeletal muscle regeneration. The process of regeneration was induced by bupivacaine injection in surgically exposed rat extensor digitorum longus (EDL) muscle. After total RNA isolation from the injected and the contralateral control EDL muscles performed 3, 7, 15 and 30 days following injection, Northern blot and RNase protection assays were carried out with four cDNA probes specific for the skeletal and cardiac muscle isoforms of both the DHPR alpha1-subunit and the RyR. After 3 days, an initial precipitous decrease in the expression of the genes encoding the skeletal muscle isoforms of the DHPR and RyR was observed, followed by an increase. Moreover, regenerating skeletal muscle transiently expressed mRNA for the DHPR cardiac isoform, mainly at the beginning of regeneration. No expression of mRNA for the cardiac RyR was observed. Contraction experiments, performed using EDL muscle at the same times after bupivacaine injection, showed that twitch amplitude was markedly decreased in the absence of external calcium, but only during the early stages of regeneration. Similar findings in relation to expression of skeletal and cardiac muscle DHPR message were previously reported from experiments conducted during early developmental stages using fetal skeletal muscle and muscle cell cultures [Chaudhari N, Beam KG (1993) Dev Biol 155:507-515]. These results suggest that expression of the DHPR cardiac isoform in skeletal muscle could explain certain cardiac-like aspects of excitation-contraction coupling of regenerating skeletal muscle and developing skeletal muscle as well.

Animals↗
PubMed2006

Regeneration in Macrostomum lignano (Platyhelminthes): cellular dynamics in the neoblast stem cell system.

Neoblasts are potentially totipotent stem cells and the only proliferating cells in adult Platyhelminthes. We have examined the cellular dynamics of neoblasts during the posterior regeneration of Macrostomum lignano. Double-labeling of neoblasts with bromodeoxyuridine and the anti-phospho histone H3 mitosis marker has revealed a complex cellular response in the first 48 h after amputation; this response is different from that known to occur during regeneration in triclad platyhelminths and in starvation/feeding experiments in M. lignano. Mitotic activity is reduced during the first 8 h of regeneration but, at 48 h after amputation, reaches almost twice the value of control animals. The total number of S-phase cells significantly increases after 1 day of regeneration. A subpopulation of fast-cycling neoblasts surprisingly shows the same dynamics during regeneration as those in control animals. Wound healing and regeneration are accompanied by the formation of a distinct blastema. These results present new insights, at the cellular level, into the early regeneration of rhabditophoran Platyhelminthes.

Amputation, Surgical↗