The effect of preconditioning on the iron deposition after transient forebrain ischemia in rat brain

In this study we investigated iron deposition in the hippocampus CA1 area and the corpus striatum pars dorsolateralis in a rat model of cerebral ischemia and ischemic tolerance. Forebrain ischemia was induced by four-vessel occlusion for 5-min as ischemic preconditioning. Two days after the preconditioning or the sham operation, a second ischemia was induced for 20-min. With the use of iron histochemistry, regional changes were examined after 2 to 8 weeks of recirculation following the 20-min ischemia with or without preconditioning. Perl's reaction with DAB intensification demonstrated iron deposits in the CA1 area and in the corpus striatum pars dorsolateralis after 2 weeks of recirculation. These iron deposits gradually increased in density and formed clusters by the 8th week. When the rats were exposed to 5-min ischemia 2 days before lethal 20-min ischemia, the deposition of iron in the CA1 region of the hippocampus and also in the corpus striatum pars dorsolateralis was decreased and produced a minimal number of iron-containing cells between the second and the 8th week of recirculation. Preconditioning with sublethal 5-min ischemia followed by 2 days of reperfusion also prevented the neuronal destruction of the hippocampal CA1 region induced by 20-min ischemia.     

Human anti-V2 monoclonal antibody that neutralizes primary but not laboratory isolates of human immunodeficiency virus type 1.

A human immunoglobulin G1 lambda monoclonal antibody (MAb), 697-D, was developed that recognizes the V2 region of human immunodeficiency virus type 1 (HIV-1) gp120. Substitutions at amino acid positions 176/177, 179/180, 183/184, and 192 to 194 in the V2 loop of gp120 each completely abolished the binding capacity of 697-D in an enzyme-linked immunosorbent assay format. Competition analysis with three different neutralizing murine anti-V2 MAbs confirmed the specificity of 697-D. The 697-D epitope is primarily conformation dependent, although there was weak reactivity of the MAb with a V2 peptide spanning residues 161 to 180. Treatment of recombinant gp120 HIVIIIB with sodium metaperiodate, which oxidizes carbohydrates, abolished the binding of the MAb, showing the dependence of the epitope on intact carbohydrates. The broad reactivity of 697-D was displayed by its binding to the gp120 molecules from four of four laboratory isolates and five of five primary isolates. The MAb 697-D neutralized three out of four primary isolates but failed to neutralize any of four laboratory strains of HIV-1. 697-D and a human anti-V3 MAb, 447-52-D, displayed similar potency in neutralizing primary isolates, indicating that the V2 region of gp120, like the V3 region and the CD4-binding domain, can induce potent neutralizing antibodies against HIV-1 in humans.     

Cochlea in old world mice and rats (Muridae)

Morphometric analysis of the cochlea was performed in wild and laboratory murids: Mus musculus, Apodemus sylvaticus, Rattus rattus, R. norvegicus, NMRI mouse, and Wistar rat. Results are based on light microscopic examination of surface specimens and serial sections and on three-dimensional computer reconstruction. The cochleae have 1.75-2.2 coils. The length of the basilar membrane varies from 6.0 to 12.1 mm. Mean density of outer hair cells ranges between 363 and 411, inner hair cells 98 and 121, neurons 1,230 and 1,760 per 1 mm. Following parameters change from base to apex: basilar membrane width 66.0 (+/- 8.2) to 175.0 (+/- 24.7) microns, basilar membrane thickness 17.0 (+/- 2.6) to 1.9 (+/- 0.1) microns, width of triad of outer hair cells 13.2 (+/- 0.7) to 28.8 (+/- 4.4) microns. The given numbers are mean "murid" values (with respective standard deviations). Maximum of dimensions of scalae is located at 10-15%, that of density of outer hair cells at 65%, density of inner hair cells at 2.8 mm, maximum of innervation density at 40-60% from the base. The following parameters are correlated with pinna size: length and maximum width of basilar membrane, dimensions of scalae, total number of receptors, and probably resolution capabilities. The following parameters are correlated with body size: maximum width of triad of outer hair cells, density and total number of neurons, ratio of neurons to receptors, apicobasal difference in basilar membrane stiffness and width of triad of outer hair cells; inversely proportional is receptor density and ratio of outer to inner hair cells and probably low-frequency cut-off. Thickness, and minimum width of basilar membrane and triad of outer hair cells and probably high-frequency cutoff are species-specific and independent of pinna or body size. The parameters mentioned indicate that the examined murids are acoustically unspecialized mammals and their cochleae approximate the generalized plan for a mammalian cochlea. Differences between domesticated and wild murids are stated.     

Non-Breeding Eusocial Mole-Rats Produce Viable Sperm—Spermiogram and Functional Testicular Morphology of Fukomys anselli

Ansell’s mole-rats (Fukomys anselli) are subterranean rodents living in families composed of about 20 members with a single breeding pair and their non-breeding offspring. Most of them remain with their parents for their lifetime and help to maintain and defend the natal burrow system, forage, and care for younger siblings. Since incest avoidance is based on individual recognition (and not on social suppression) we expect that non-breeders produce viable sperm spontaneously. We compared the sperm of breeding and non-breeding males, obtained by electroejaculation and found no significant differences in sperm parameters between both groups. Here, we used electroejaculation to obtain semen for the first time in a subterranean mammal. Spermiogram analysis revealed no significant differences in sperm parameters between breeders and non-breeders. We found significantly larger testes (measured on autopsies and on living animals per ultrasonography) of breeders compared to non-breeders (with body mass having a significant effect). There were no marked histological differences between breeding and non-breeding males, and the relative area occupied by Leydig cells and seminiferous tubules on histological sections, respectively, was not significantly different between both groups. The seminiferous epithelium and to a lesser degree the interstitial testicular tissue are characterized by lesions (vacuolar degenerations), however, this feature does not hinder fertilization even in advanced stages of life. The continuous production of viable sperm also in sexually abstinent non-breeders might be best understood in light of the mating and social system of Fukomys anselli, and the potential to found a new family following an unpredictable and rare encounter with an unfamiliar female (“provoked or induced dispersal”). Apparently, the non-breeders do not reproduce because they do not copulate but not because they would be physiologically infertile. The significantly increased testes volume of breeding males (compared to non-breeders) is in agreement with previously found higher testosterone levels of breeders.     

Constraints of pregnancy and evolution of sociality in mole-rats With special reference to reproductive and social patterns in Cryptomys hottentotus (Bathyergidae,Rodentia)1

Described: basic characteristics of reproduction and pre- and postnatal growth rate and development in Zambian mole-rats, Crypromys hottentotus (Bathyergidae), and compared with the available data on other small subterranean hystricognathous rodents. It is demonstrated that C. hottentotus from relatively rnesic habitats are monoamous and eusocial. The animals in each colony may be divided into several cateories according to their body size and pelage colouration (polymorhim) and prevailing beiavioural pattern (polyethism). Particularly breeding animals are sexually dimorphic. Freuent sexual interactions can be noted in the breeding pair even outside the female's estrus. Growth and sexual behaviour are pheromonally suppressed in the offspring (subordinate animals by their mutual contact and, particularly, by the parents (dominant animals). Most eflicient supression of growth is accomplished by a lactating female. It is arued that eusociality of the naked mole-rat, Heterocephalus glaber, is not qualitatively unique and has not evolved as an immediate response to aridity and dispersed food resources as generally considered. Evidence is presented that eusociality may have evolved as a direct consequence of decreasing the body size combined with retention of a long developmental time (phylogenetic constraint), limitations to store fat reserves, reduction of female's activit and consequent constraints of prenancy. Gestation had to be shortened at the cost of bearing altricial young and prolongation of tie postnatal development. Monogamy and establishment of a caste of helpers may be understood as energy-saving mechanisms of breeding females. Eusociality may be useful for survival in arid habitats, yet reasons for origin should te distinguished from the current (manifold) utility.     

Life History and Secondary Production of Mayflies (Ephemeroptera) Indicate Disturbance in Two Small Carpathian Streams

The life histories and the secondary production of 9 mayflies (Ephemeroptera) species were studied at two sites in a submountain stream (West Carpathians, Slovakia). The disturbed site has a deforested and converted to meadows and pastures catchment and the undisturbed one is a well‐preserved submountain stream with 60% of the catchment covered by spruce forests. Differences in the forest cover and in the thermal regime of both streams were reflected in the structural as well as the functional measures. At the undisturbed site, the total secondary production of mayfly community was more than two times higher (3568 mg DW m^–2 y^–1) than at the disturbed site (1446 mg DW m^–2 y^–1). Species could be divided according to their affinity to particular disturbance level. Ecdyonurus picteti, Rhithrogena carpatoalpina, Habrophlebia lauta and Habroleptoides confusa appeared to prefer undisturbed conditions. On the contrary, Ecdyonurus aurantiacus and Habrophlebia fusca occurred only at the disturbed site. The dominant species Baetis rhodani and Electrogena samalorum did not show any clear preference regarding the catchment disturbance. However, nymphs of Electrogena samalorum seem to be more successful at the disturbed site, where they reached bigger body sizes (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The dynamics of the non-heme iron in bacterial reaction centers from Rhodobacter sphaeroides

We investigate the dynamical properties of the non-heme iron (NHFe) in His-tagged photosynthetic bacterial reaction centers (RCs) isolated from Rhodobacter (Rb.) sphaeroides. M?ssbauer spectroscopy and nuclear inelastic scattering of synchrotron radiation (NIS) were applied to monitor the arrangement and flexibility of the NHFe binding site. In His-tagged RCs, NHFe was stabilized only in a high spin ferrous state. Its hyperfine parameters (IS=1.06±0.01mm/s and QS=2.12±0.01mm/s), and Debye temperature (θ(D0)~167K) are comparable to those detected for the high spin state of NHFe in non-His-tagged RCs. For the first time, pure vibrational modes characteristic of NHFe in a high spin ferrous state are revealed. The vibrational density of states (DOS) shows some maxima between 22 and 33meV, 33 and 42meV, and 53 and 60meV and a very sharp one at 44.5meV. In addition, we observe a large contribution of vibrational modes at low energies. This iron atom is directly connected to the protein matrix via all its ligands, and it is therefore extremely sensitive to the collective motions of the RC protein core. A comparison of the DOS spectra of His-tagged and non-His-tagged RCs from Rb. sphaeroides shows that in the latter case the spectrum was overlapped by the vibrations of the heme iron of residual cytochrome c(2), and a low spin state of NHFe in addition to its high spin one. This enabled us to pin-point vibrations characteristic for the low spin state of NHFe.     

Transduction with recombinant adeno-associated virus for gene therapy is limited by leading-strand synthesis.

Adeno-associated virus is an integrating DNA parvovirus with the potential to be an important vehicle for somatic gene therapy. A potential barrier, however, is the low transduction efficiencies of recombinant adeno-associated virus (rAAV) vectors. We show in this report that adenovirus dramatically enhances rAAV transduction in vitro in a way that is dependent on expression of early region 1 and 4 (E1 and E4, respectively) genes and directly proportional to the appearance of double-stranded replicative forms of the rAAV genome. Expression of the open reading frame 6 protein from E4 in the absence of E1 accomplished a similar but attenuated effect. The helper activity of adenovirus E1 and E4 for rAAV gene transfer was similarly demonstrated in vivo by using murine models of liver- and lung-directed gene therapy. Our data indicate that conversion of a single-stranded rAAV genome to a duplex intermediate limits transduction and usefulness for gene therapy.     

Higher resting metabolic rate in long-lived breeding Ansell’s mole-rats (<Emphasis Type="Italic">Fukomys anselli</Emphasis>)

Background

Reproduction is an energetically expensive process that supposedly impairs somatic integrity in the long term, because resources are limited and have to be allocated between reproduction and somatic maintenance, as predicted by the life history trade-off model. The consequence of reduced investment in somatic maintenance is a gradual deterioration of function, i.e. senescence. However, this classical trade-off model gets challenged by an increasing number of contradicting studies. Here we report about an animal model, which adds more complexity to the ongoing debate. Ansell’s mole-rats are long-lived social subterranean rodents with only the founder pair reproducing, while most of their offspring remain in the parental burrow system and do not breed. Despite of a clear reproductive trade-off, breeders live up to twice as long as non-breeders, a unique feature amongst mammals.

Methods

We investigated mass-specific resting metabolic rates (msRMR) of breeders and non-breeders to gain information about the physiological basis underlying the reproduction-associated longevity in Ansell’s mole-rats. We assessed the thermoneutral zone (TNZ) for breeders and non-breeders separately by means of indirect calorimetry. We applied generalized linear mixed-effects models for repeated measurements using the msRMR in the respective TNZs.

Results

TNZ differed between reproductive and non-reproductive Ansell’s mole-rats. Contrary to classical aging models, the shorter-lived non-breeders had significantly lower msRMR within the thermoneutral zone compared to breeders.

Conclusion

This is the first study reporting a positive correlation between msRMR and lifespan based on reproductive status. Our finding contradicts common aging theories, but supports recently introduced models which do not necessarily link reproductive trade-offs to lifespan reduction.