Corridors of migrating neurons in the human brain and their decline during infancy

The subventricular zone of many adult non-human mammals generates large numbers of new neurons destined for the olfactory bulb. Along the walls of the lateral ventricles, immature neuronal progeny migrate in tangentially oriented chains that coalesce into a rostral migratory stream (RMS) connecting the subventricular zone to the olfactory bulb. The adult human subventricular zone, in contrast, contains a hypocellular gap layer separating the ependymal lining from a periventricular ribbon of astrocytes. Some of these subventricular zone astrocytes can function as neural stem cells in vitro, but their function in vivo remains controversial. An initial report found few subventricular zone proliferating cells and rare migrating immature neurons in the RMS of adult humans. In contrast, a subsequent study indicated robust proliferation and migration in the human subventricular zone and RMS. Here we find that the infant human subventricular zone and RMS contain an extensive corridor of migrating immature neurons before 18 months of age but, contrary to previous reports, this germinal activity subsides in older children and is nearly extinct by adulthood. Surprisingly, during this limited window of neurogenesis, not all new neurons in the human subventricular zone are destined for the olfactory bulb--we describe a major migratory pathway that targets the prefrontal cortex in humans. Together, these findings reveal robust streams of tangentially migrating immature neurons in human early postnatal subventricular zone and cortex. These pathways represent potential targets of neurological injuries affecting neonates.     

Temperature and high salinity effects in germinating dimorphic seeds of Atriplex rosea

Atriplex rosea L. (Chenopodiaceae; tumbling orach), an annual herb, is a widely established weedy species of disturbed sites in all counties of Utah. Seeds of Atriplex rosea were collected from a salt marsh in Faust, Utah, and are dimorphic, light brown, and 2-2.5 mm wide, or black and 1-2 mm wide. Seed germination responses of the black and brown seeds were studied over a range of salinity and temperature. Both brown and black seeds germinated at 1000 mM NaCl, and the optimal temperature for germination of both types was 20°-30°C. Variation in temperature, however, affected germination of black seeds more than brown seeds. At lower thermoperiod only 40%-50% black seeds germinated in nonsaline control, and germination was almost completely inhibited with the inclusion of salinity. However, all brown seeds germinated in control at temperatures above 5°-15°C, and inhibition caused by salinity was comparatively lower. Brown seeds had a higher germination rate than black seeds at all temperature and salinity treatments. The highest rate of germination of both seeds occurred at the temperature regime of 5°-15°C. Recovery of germination for black seeds when transferred to distilled water after being in various salinity treatments for 20 days was quite variable. Recovery decreased with increase in salinity at lower temperature regimes, increased with salinity at optimal thermoperiod, and had no effect at 20°-30°C. Brown seeds recovered poorly from salinity at all thermoperiods except 5°-15°C, where recovery decreased with an increase in salinity. Brown seeds are adapted to germination in the early part of the growing season, whereas black seeds are capable of surviving harsher conditions and can germinate in later time periods. Characteristics of the dimorphic seeds increase chances for survival in the harsh saline desert environment.     

AN INVESTIGATION OF THE RELATION BETWEEN COTTON FIBRE PROPERTIES AND YARN QUALITY BY USING HIGH VOLUME INSTRUMENT(HVI)SYSTEM

The objective of this paper is to establish reliable prediction equations relating cotton fibreproperties measured by HVI system and yarn quality,A useful statistical method is adopted for de-veloping a multiple regression model interpreting the relation between the data of Spinlab HVIfibre properties and quality parameters of yarn STQ (Strength Tex Quotient).The percent relativecontribution of a fibre property with respect of STQ is also assessed.The results show that the totalcontribution of the HVI measured fibre properties can account for 77.4% of known variation ofyarn STQ.The main feature of the approach is its flexibility in accommodating all fibre properties.The examination of regression equation showed that it could be well applied to predict STQ ofyarns spun from the same spinning system,but,for different spinning systems and also for yarns ofdifferent linear density,modification of the equation would be needed.     

The agar gel-diffusion technique as a method of differentiating mosquito eggs

Zusammenfassung Bei Agargel-Diffusionstechnik zeigenCulex-pipiens-fatigans-Eier mindestens vier deutlich voneinander unterscheidbare Präzipitationslinien, wenn sie mit homologem Antiserum reagierten. Eier vonArmigeres subalbatus, Aedes aegypti undAedes albopictus hingegen zeigten nur eine einzige Linie bei Reaktion mit dem gleichenCulex-Antiserum.     

The application of fluorescent-antibody test to cysts ofEntamoeba invadens

Zusammenfassung Die Methode fluoreszierender Antikörper wurde zur Darstellung von Blasen beiEntamoeba invadens benützt. Sowohl mit nativen, wie auch mit fixierten Zellen konnte eine befriedigende Reaktion erzielt werden. Formalin erwies sich als günstigstes Fixationsmittel.     

The lytic activity of immune and non-immune rabbit serum onBalantidium coli

Résumé Des bacillesBalantidium coli ont été dissous après avoir été exposés à l'action du sérum de lapin immunisé et non-immunise. L'activité lytique des 2 sérums se perd par inactivation thermique à 56°C pendant 30 min, mais elle est restorée dans les 2 sérums après adjonction de sérum de cobaye normal.     

Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants. Here we demonstrate a low-temperature (650 degrees C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m(2) g(-1)), and contained a significant population of micropores (< or =20 A). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological or synthetic silica templates for sensor, electronic, optical or biomedical applications.