MUC4 involvement in ErbB2/ErbB3 phosphorylation and signaling in response to airway cell mechanical injury

The receptor tyrosine kinases ErbB2 and ErbB3 are phosphorylated in response to injury of the airway epithelium. Since we have shown that the membrane mucin MUC4 can act as a ligand/modulator for ErbB2, affecting its localization in polarized epithelial cells and its phosphorylation, we questioned whether Muc4 was involved, along with ErbB2 and ErbB3, in the damage response of airway epithelia. To test this hypothesis, we first examined the localization of MUC4 in human airway samples. Both immunocytochemistry and immunofluorescence showed a co‐localization of MUC4 and ErbB2 at the airway luminal surface. Sequential immunoprecipitation and immunoblotting from airway cells demonstrated that the MUC4 and ErbB2 are present as a complex in airway epithelial cells. To assess the participation of MUC4 in the damage response, cultures of NCI‐H292 or airway cells were scratch‐wounded, then analyzed for association of phospho‐ErbB2 and ‐ErbB3 with MUC4 by sequential immunoprecipitation and immunoblotting. Wounded cultures exhibited increased phosphorylation of both receptors in complex with MUC4. Scratch wounding also increased activation of the downstream pathway through Akt, as predicted from our previous studies on Muc4 effects on ErbB2 and ErbB3. The participation of MUC4 in the phosphorylation response was also indicated by siRNA repression of MUC4 expression, which resulted in diminution of the phosphorylation of ErbB2 and ErbB3. These studies provide a new model for the airway epithelial damage response, in which the MUC4–ErbB2 complex is a key element in the sensor mechanism and phosphorylation of the receptors. J. Cell. Biochem. 107: 112–122, 2009. © 2009 Wiley‐Liss, Inc.     

Ortstreue und Genflu? bei Inselvogelarten: Eleonorenfalke (Falco eleonorae) und Gelbschnabelsturmtaucher (Calonectris diomedea)

Summary Young birds of both species return almost exclusively to their natal colony for breeding and breeders are higly faithful to both partner and territory in subsequent years. There is no or very limited emigration to other colonies which are 2–5 km distant. The consequences of the genetic isolation are discussed: In both species the tendency to form subspecies can be detected. High mortality rates are interpreted as a mean to eliminate any degenerated bird which could result from the close interbreeding in these small and isolated populations.     

Epididymal maturation and the acrosome reaction in mouse sperm: response to zona pellucida develops coincident with modification of M42 antigen

Development of the sperm's capacity to interact with the zona pellucida was investigated at the stage when the acrosome reaction (AR) is induced. The response of epididymal sperm to agents that affect the occurrence of the AR was used to monitor maturational changes. Despite the finding that sperm from the three main epididymal regions were competent to undergo ARs induced by the divalent cation ionophore A23187 (56% AR, 74% AR, and 83% AR in caput, corpus, and cauda, respectively), the cells' responses to solubilized zonae pellucidae were different. When challenged with 5 zonae equivalents/microliter, both corpus and cauda sperm shed their acrosomes in high numbers (75% AR and 86% AR, respectively), whereas caput sperm did not (23% AR). Previous work has shown that the presence of M42 monoclonal antibody (mAb) during in vitro and in vivo fertilization inhibits sperm penetration through the zona pellucida by specific interference with zonae pellucidae-induced ARs. In this study, presence of the M42 mAb did not affect the incidence of A23187-induced ARs, whereas the zona-induced ARs that occurred in both corpus and cauda sperm were inhibited fully with M42 immunoglobulin (Ig) G. In addition, the antigen recognized by M42 mAb on sperm, termed M42 Ag, was examined during epididymal maturation. Although antigen localization appeared indistinguishable by immunofluorescence on sperm taken from the caput, corpus, and cauda regions of the epididymis, modification of this antigen during epididymal transit was detected. Equilibrium-binding studies using 125I-M42 IgG demonstrated a progressive increase during epididymal transit in the amount of M42 mAb that bound to fixed cells. Corpus and cauda sperm bound 185% and 240%, respectively, of the 125I-M42 IgG detected on caput sperm. These changes in expression of M42 Ag paralleled a structural change: the Mr of the antigen decreased from a 195,000/210,000 doublet in caput sperm to a 185,000/200,000 doublet in corpus and cauda sperm, as determined by immunoblot analysis of sodium dodecyl sulfate (SDS)-extracted sperm. Results presented here demonstrate that mouse sperm develop the capacity to undergo a zona-induced AR during epididymal maturation. The M42 antigen, which is involved in the zona-induced AR, is modified during epididymal transit coincident with development of the sperm's responsiveness to zonae. Our working hypothesis, based on these results, is that development of the sperm's capacity to undergo a physiological AR is related to modification of M42 Ag.     

Use of calcium to optimize long-term proliferation of friable embryogenic calluses and plant regeneration in Hevea brasiliensis (Mll. Arg.)

In Hevea brasiliensis (Mll. Arg.), increasing the calcium contentof the friable callus maintenance medium from 3 to 9 mM stimulatedregeneration potential through somatic embryogenesis. This stimulationcould be attributed to the homogeneous cytological structureof calluses, which were formed of undifferentiated cells capableof somatic embryogenesis in optimal culture conditions. Thevery marked increase in the active cell population was sufficientto cause a decrease and a stabilization of water and osmoticpotentials of the calluses, whereas their water content increased.The regeneration capacity of calluses cultured on a medium withadditional CaCl₂ was greater in terms of both quantity (numberof somatic embryos produced was increased 2-fold) and quality(germination efficiency trebled). High CaCl₂ concentrations (9 mM CaCl₂) in the embryogenesisinduction medium favoured somatic embryo development when calluseswere maintained 2 months on the same medium. In this case, additionof benzylaminopurine (BAP) and 3,4-dichlorophenoxy- acetic acid(3,4-D) increased the number of embryos produced (243 embryosg^–1 FW callus) and their germination capacity (27%). These culture conditions were used to determine the optimumembryogenesis induction period. The length of the period affectedboth the intensity of embryogenesis (maximum 56–77 d)and somatic embryo quality (maximum 49–70 d). The bestresults were obtained with a 70 d embryogenesis induction period,within which 355 embryos g^–1 FW callus were obtained,with 35% germination. Key words: Calcium, somatic embryogenesis, long-term culture, water status, histology     

The physiology of the ovary: Maturation of ovarian granulosa cells and a novel role for antioxidants in the corpus luteum

During folliculogenesis the granulosa cells divide whilst in contact with each other, and so exhibit some of the characteristics of stem cells. In vitro we have shown that bovine granulosa cells from 3–7 mm follicles, like stem cells, divide without the need for a substratum, and produce colonies of cells. Growth factors, bFGF and IGF's, stimulate their division. These cells secrete and assemble a basal lamina, suggesting that the follicular basal lamina is produced by the granulosa cells. They have the morphological characteristics of follicular granulosa cells. Thus this system is ideal for studying the functions of immature granulosa cells because the cells do not spontaneously differentiate or luteinize into luteal cells, as occurs in culture on a substratum. On differentiation into luteal cells in vivo the cells express the steroidogenic enzymes for progesterone production and accumulate β-carotene. During culture of bovine luteal cells we observed that a proportion of the steroidogenic enzyme cholesterol side-chain cleavage cytochrome P450 enzyme became chemically cross-linked to its electron donor, adrenodoxin. P450 enzymes produce oxygen free radicals and oxygen free radicals can cause cross-linking between proteins in close proximity. Cell protect against this damage by the use of antioxidant vitamins. Repleting the cultured luteal cells with β-carotene reduced the amount of cross-linking. We conclude that the high levels of β-carotene in corpora lutea are to protect against damage due to oxygen free radicals generated in the course of progesterone synthesis.     

Biologie des Eleonorenfalken(Falco eleonorae): 10. Der Einflu? der Horstlage auf den Bruterfolg

Zusammenfassung Der Bruterfolg des Eleonorenfalken wurde auf einer ägäischen Inselkolonie in Relation zur Horstlage untersucht. Bei Horsten mit Gratlage auf übersichtlichem Gelände war er signifikant höher (1,8 Junge/Horst) als bei den übrigen Horsten mit z. T. schlechtem Geländeüberblick (1,3 Junge/Horst). Da alle Horste gegenüber den NW-Winden geschützt lagen, waren die meisten an südlich ausgerichteten Hängen potentiell der intensiven Sonneneinstrahlung ausgesetzt. In den Horstrevieren von typisch 20 m Durchmesser gab es aber nicht immer vor Sonne geschützte Horsthöhlen, so daß bei Lufttemperaturen von 40 °C und Bodentemperaturen von bis zu 60 °C die Embryonen in den Eiern gefährdet sein können, besonders, wenn sie der direkten Sonneneinstrahlung ausgesetzt sind. Dies tritt z. B. bei einer Störung in der Brutkolonie ein. Der Bruterfolg in den sonnenexponierten Höhlen lag mit 0,8–1,3 Junge/Horst signifikant niedriger als in den sonnengeschützten Höhlen mit durchschnittlich 1,75 Junge/Horst. Neben einer normalen Infertilität von 10 % fielen weitere 8 % aller Eier in der Brutkolonie durch Sonneneinwirkung aus.

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Biology of the Eleonora's Falcon(Falco eleonorae): 10. Breeding success in relation to nest site exposition

Summary Breeding success of the Eleonora's Falcon was studied in an Aegean island colony. In nests near cliff tops with an unobstructed view of the surroundings, a significantly higher breeding success (1.8 pulli/nest) was obtained than in other nests (1.3 pulli/nest). Since all nests were chosen protected from the wind, and as the main wind comes from NW, most nests were situated on southern slopes and are thus potentially exposed to the sun. Within a falcon territory of typically 20 m diameter in size there was not always a lime stone crevice with complete shade for the eggs. At an air temperature of 40 °C and a soil temperature of up to 60 °C, excessive sunning of an unprotected egg can be lethal for the falcon embryo. Breeding success in sun exposed nests was significantly lower (0.8–1.3 pulli/nest) than in sheltered nests (1.75 pulli/nest). In addition to a normal infertility of 10 %, about 8 % of all eggs laid were lost due to sun irradiation.

     

Increased Rubisco content in maize mitigates chilling stress and speeds recovery

Many C₄ plants, including maize, perform poorly under chilling conditions. This phenomenon has been linked in part to decreased Rubisco abundance at lower temperatures. An exception to this is chilling‐tolerant Miscanthus, which is able to maintain Rubisco protein content under such conditions. The goal of this study was to investigate whether increasing Rubisco content in maize could improve performance during or following chilling stress. Here, we demonstrate that transgenic lines overexpressing Rubisco large and small subunits and the Rubisco assembly factor RAF1 (RAF1‐LSSS), which have increased Rubisco content and growth under control conditions, maintain increased Rubisco content and growth during chilling stress. RAF1‐LSSS plants exhibited 12% higher CO₂ assimilation relative to nontransgenic controls under control growth conditions, and a 17% differential after 2 weeks of chilling stress, although assimilation rates of all genotypes were ~50% lower in chilling conditions. Chlorophyll fluorescence measurements showed RAF1‐LSSS and WT plants had similar rates of photochemical quenching during chilling, suggesting Rubisco may not be the primary limiting factor that leads to poor performance in maize under chilling conditions. In contrast, RAF1‐LSSS had improved photochemical quenching before and after chilling stress, suggesting that increased Rubisco may help plants recover faster from chilling conditions. Relatively increased leaf area, dry weight and plant height observed before chilling in RAF1‐LSSS were also maintained during chilling. Together, these results demonstrate that an increase in Rubisco content allows maize plants to better cope with chilling stress and also improves their subsequent recovery, yet additional modifications are required to engineer chilling tolerance in maize.     

Influence of prior and visual information on eye movements in amblyopic children

This study analyzed the characteristics of pursuit and assessed the influence of prior and visual information on eye velocity and saccades in amblyopic and control children, in comparison to adults. Eye movements of 41 children (21 amblyopes and 20 controls) were compared to eye movements of 55 adults (18 amblyopes and 37 controls). Participants were asked to pursue a target moving at a constant velocity. The target was either a ‘standard’ target, with a uniform color intensity, or a ‘noisy’ target, with blurry edges, to mimic the blurriness of an amblyopic eye. Analysis of pursuit patterns showed that the onset was delayed, and the gain was decreased in control children with a noisy target in comparison to amblyopic or control children with a standard target. Furthermore, a significant effect of prior and visual information on pursuit velocity and saccades was found across all participants. Moreover, the modulation of the effect of visual information on the pursuit velocity by group, that is amblyopes or controls with a standard target, and controls with a noisy target, was more limited in children. In other words, the effect of visual information was higher in control adults with a standard target compared to control children with the same target. However, in the case of a blurry target, either in control participants with a noisy target or in amblyopic participants with a standard target, the effect of visual information was larger in children.