Molecular analysis of a pistil-specific gene expressed in the stigma and stylar cortex of Solanum tuberosum

A gene, sts14, coding for a highly expressed mRNA in pistils of Solanum tuberosum, was isolated. Northern blot and in situ analyses demonstrated that the gene was expressed throughout pistil development in both the stylar cortex and the stigma. The deduced STS14 protein displays similarity to the pathogenesis-related PR-1 proteins. A possible function for protection or guidance of the pollen tubes through the pistil is discussed.     

Measurement of oxygen tension changes in the style during pollen tube growth

Summary Using a Clark micro electrode the actual oxygen tension at various places in a style can be measured. Within the unpollinated, ripe style of Hippeastrum a pO₂ gradient occurs. In the upper part, possibly with a little increase in the stigmatic branches, a very high oxygen tension is found; in the lower part, about 5 mm from the ovary, a sudden decrease occurs. In the ovary itself the oxygen tension is extremely low. After pollination, passage of the mass of pollen tube tips can be followed by a fairly sharp drop of the oxygen tension, which shifts down the style with progressive growth. This oxygen tension depression seems to be sharply limited to the region of pollen tube tips and the amount of decrease is dependent on the growth rate of the tubes. After passage of the pollen the original high level of oxygen tension is not fully restored in the upper style. This suggests that the metabolic activity of the pollen tube is strongly linked with the metabolic condition in the style. It seems that tubes grow most of their way to the egg under aerobic conditions; only at the base of the style, just before entering into the ovary, does the pollen have to switch over to an anaerobic pathway. For most of the style oxygen tension does not form a tropic gradient for tube growth.

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Zusammenfassung Unter Benutzung einer Clark-Mikro-Elektrode konnte die aktuelle Sauerstoffspannung an verschiedenen Stellen in einem Griffel in situ gemessen werden. Dabei wurde im reifen, unbestäubten Griffel von Hippeastrum ein pO₂-Gradient gefunden: Im oberen Griffelabschnitt, wahrscheinlich mit einer kleinen Depression in den Narbenästen, wurde eine sehr hohe Sauerstoff-Spannung gefunden; im unteren Teil, etwa 5 mm über dem Fruchtknoten beginnend, nimmt der pO₂-Wert plötzlich schnell ab. Im Fruchtknoten selber ist die Sauerstoffspannung extrem niedrig.Nach Bestäubung kann das Durchwachsen der Masse der Pollenschlauchspitzen an Hand einer scharfen Depression der Sauerstoffspannung verfolgt werden, welche mit fortschreitendem Wachstum im Griffel nach unten zu verschoben wird. Diese Depression des pO₂-Wertes scheint streng lokalisiert zu sein auf den Bereich der Pollenschlauchspitzen; die Größe der Depression ist abhängig von der Wachstumsgeschwindigkeit der Pollenschläuche. Nach dem Durchwachsen der Pollenschläuche wird die ursprünglich hohe Sauerstoffspannung in den oberen Griffelabschnitten nicht vollständig wiederhergestellt.Aus den Meßergebnissen kann der Schluß gezogen werden, daß die Stoffwechselaktivität der Pollenschläuche in hohem Maße abhängt von den Stoffwechselbedingungen im Innern des Griffels. Es scheint, daß die Pollenschläuche auf dem größten Teil ihres Weges zu den Eizellen unter aeroben Bedingungen wachsen; lediglich an der Basis des Griffels, kurz vor dem Eintritt in das Ovarium, muß der Pollenschlauch umschalten auf einen anaeroben Energiestoffwechsel. Ein Zusammenhang mit der Öffnung der Pollenschlauchspitzen bei der Entleerung des Schlauchinhaltes in den Embryosack wird diskutiert.Die Sauerstoffspannung scheint für den größten Teil des Griffels nicht die Funktion eines tropischen Gradienten für das orientierte Pollenschlauchwachstum zu haben.

     

Small Hydrophobic Protein of Human Metapneumovirus Does Not Affect Virus Replication and Host Gene Expression In Vitro

Human metapneumovirus (HMPV) encodes a small hydrophobic (SH) protein of unknown function. HMPV from which the SH open reading frame was deleted (HMPVΔSH) was viable and displayed similar replication kinetics, cytopathic effect and plaque size compared with wild type HMPV in several cell-lines. In addition, no differences were observed in infection efficiency or cell-to-cell spreading in human primary bronchial epithelial cells (HPBEC) cultured at an air-liquid interphase. Host gene expression was analyzed in A549 cells infected with HMPV or HMPVΔSH using microarrays and mass spectrometry (MS) based techniques at multiple time points post infection. Only minor differences were observed in mRNA or protein expression levels. A possible function of HMPV SH as apoptosis blocker, as proposed for several members of the family Paramyxoviridae, was rejected based on this analysis. So far, a clear phenotype of HMPV SH deletion mutants in vitro at the virus and host levels is absent.     

A novel variant in DMXL2 gene is associated with autosomal dominant non-syndromic hearing impairment (DFNA71) in a Cameroonian family

Approximately half of congenital hearing impairment cases are inherited, with non-syndromic hearing impairment (NSHI) being the most frequent clinical entity of genetic hearing impairment cases. A family from Cameroon with NSHI was investigated by performing exome sequencing using DNA samples obtained from three family members, followed by direct Sanger sequencing in additional family members and controls participants. We identified an autosomal dominantly inherited novel missense variant [NM_001174116.2:c.918G>T; p.(Q306H)] in DMXL2 gene (MIM:612186) that co-segregates with mild to profound non-syndromic sensorineural hearing impairment . The p.(Q306H) variant which substitutes a highly conserved glutamine residue is predicted deleterious by various bioinformatics tools and is absent from several genome databases. This variant was also neither found in 121 apparently healthy controls without a family history of hearing impairment , nor 112 sporadic NSHI cases from Cameroon. There is one previous report of a large Han Chinese NSHI family that segregates a missense variant in DMXL2. The present study provides additional evidence that DMXL2 is involved in hearing impairment etiology, and we suggest DMXL2 should be considered in diagnostic hearing impairment panels.     

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.