Wound healing and blastema formation in regenerating digit tips of adult mice

Amputation of the distal region of the terminal phalanx of mice causes an initial wound healing response followed by blastema formation and the regeneration of the digit tip. Thus far, most regeneration studies have focused in embryonic or neonatal models and few studies have examined adult digit regeneration. Here we report on studies that include morphological, immunohistological, and volumetric analyses of adult digit regeneration stages. The regenerated digit is grossly similar to the original, but is not a perfect replacement. Re-differentiation of the digit tip occurs by intramembranous ossification forming a trabecular bone network that replaces the amputated cortical bone. The digit blastema is comprised of proliferating cells that express vimentin, a general mesenchymal marker, and by comparison to mature tissues, contains fewer endothelial cells indicative of reduced vascularity. The majority of blastemal cells expressing the stem cell marker SCA-1, also co-express the endothelial marker CD31, suggesting the presence of endothelial progenitor cells. Epidermal closure during wound healing is very slow and is characterized by a failure of the wound epidermis to close across amputated bone. Instead, the wound healing phase is associated with an osteoclast response that degrades the stump bone allowing the wound epidermis to undercut the distal bone resulting in a novel re-amputation response. Thus, the regeneration process initiates from a level that is proximal to the original plane of amputation.     

Biometric methods for species recognition in <Emphasis Type="Italic">Trigonia</Emphasis> Bruguière (Bivalvia; Trigoniidae): a case study from the Upper Jurassic of Western Europe

From its first occurrence in the Middle Triassic to the Late Cretaceous, and thus for almost 200 Ma, Trigonia, type genus of the family Trigoniidae, has been a common constituent of global shallow-marine benthic faunas. The genus is highly over-split at the species level, which hampers sound biostratigraphic, palaeobiogeographic, and palaeoecologic applications. The present study focuses on two closely related species, i.e. Trigonia reticulata Agassiz and Trigonia pseudomeriani Choffat, and illustrates typical problems of species identification in Trigonia. T. reticulata is a well-known representative of the genus with a significant fossil record in Lower Oxfordian to Upper Kimmeridgian strata of western and central Europe, and likely is the ancestor of T. pseudomeriani, which is endemic to the Upper Oxfordian to Lower Kimmeridgian Alcobaça formation of the Lusitanian Basin (central Portugal). In order to effectively display intraspecific variability, digital analyses of a set of metric and non-metric parameters, including outline analysis, were applied to a representative number of specimens from different localities and stages. Originally, these methods were intended to show that both forms are conspecific. Instead, the analysis supports the distinctness of both species based on a very limited number of non-plastic characters. The methods applied can be transferred to other species in Trigonia and may lead to a modern species concept for the genus. Also, they may be successfully applied to other members of the Trigoniinae.     

Polymersomes Containing Iron Sulfide (FeS) as Primordial Cell Model

According to Wächtershäuser??s ??Iron-Sulfur-World?? one major requirement for the development of life on the prebiotic Earth is compartmentalization. Vesicles spontaneously formed from amphiphilic components containing a specific set of molecules including sulfide minerals may have lead to the first autotrophic prebiotic units. The iron sulfide minerals may have been formed by geological conversions in the environment of deep-sea volcanos (black smokers), which can be observed even today. Wächtershäuser postulated the evolution of chemical pathways as fundamentals of the origin of life on earth. In contrast to the classical Miller-Urey experiment, depending on external energy sources, the ??Iron-Sulfur-World?? is based on the catalytic and energy reproducing redox system $ FeS + {H_2}S \to FeS{}_2 + {H_2} $ . The energy release out of this redox reaction (?_RG°?=??38 kJ/mol, pH 0) could be the cause for the subsequent synthesis of complex organic molecules and the precondition for the development of more complex units similar to cells known today. Here we show the possibility for precipitating iron sulfide inside vesicles composed of amphiphilic block-copolymers as a model system for a first prebiotic unit. Our findings could be an indication for a chemoautotrophic FeS based origin of life.     

Store-operated Ca entry and depolarization explain the anomalous behaviour of myometrial SR: Effects of SERCA inhibition on electrical activity,Ca and force

In the myometrium SR Ca²⁺ depletion promotes an increase in force but unlike several other smooth muscles, there is no Ca²⁺ sparks-STOCs coupling mechanism to explain this. Given the importance of the control of contractility for successful parturition, we have examined, in pregnant rat myometrium, the effects of SR Ca²⁺-ATPase (SERCA) inhibition on the temporal relationship between action potentials, Ca²⁺ transients and force. Simultaneous recording of electrical activity, calcium and force showed that SERCA inhibition, by cyclopiazonic acid (CPA 20 μM), caused time-dependent changes in excitability, most noticeably depolarization and elevations of baseline [Ca²⁺]_i and force. At the onset of these changes there was a prolongation of the bursts of action potentials and a corresponding series of Ca²⁺ spikes, which increased the amplitude and duration of contractions. As the rise of baseline Ca²⁺ and depolarization continued a point was reached when electrical and Ca²⁺ spikes and phasic contractions ceased, and a maintained, tonic force and Ca²⁺ was produced. Lanthanum, a non-selective blocker of store-operated Ca²⁺ entry, but not the L-type Ca²⁺ channel blocker nifedipine (1–10 μM), could abolish the maintained force and calcium. Application of the agonist, carbachol, produced similar effects to CPA, i.e. depolarization, elevation of force and calcium. A brief, high concentration of carbachol, to cause SR Ca²⁺ depletion without eliciting receptor-operated channel opening, also produced these results. The data obtained suggest that in pregnant rats SR Ca²⁺ release is coupled to marked Ca²⁺ entry, via store operated Ca²⁺ channels, leading to depolarization and enhanced electrical and mechanical activity.     

Vergleichende Untersuchung der Proteinasen zweier Bacillus-Arten (Bacillus subtilis und Bacillus cereus)

Ohne ZusammenfassungTeil der Dissertation, Universität Frankfurt am Main 1958.     

Die Mooswelt des Ködnitztales in den Hohen Tauern

Ohne Zusammenfassung     

Ueber den Blütenbau derAdoxa Moschatellina L.

Ohne Zusammenfassung