A high-density differential screening strategy for identification of fovea genes with altered expression in the retina during aging

A human fovea cDNA library was arrayed at high-density and reacted with age-specific (4 yr & 80 yr) retinal probes to identify genes with altered expression during aging. Using this approach, we screened 55,368 genes by Southern analysis and determined that 0.7% are differentially expressed in young and old tissues. Northern analysis of total RNA from retina of humans aged 2–94 yr show that expression of one of the clones identified (clone dd₁₁₂) decreases with aging.     

长角血蜱不同发育期盾窝超微结构的比较研究

为阐明蜱类盾窝及其发育特点,用扫描电镜观察了长角血蜱Haemaphysalis longicornis不同发育期盾窝的结构,并分析了血餐对盾窝发育的影响.结果表明：幼蜱仅具1对盾窝原基,且每个盾窝原基有1个盾窝孔;若蜱盾窝有了一定的发育,面积（长径×短径）增大且盾窝孔数增多（2~6个）;成蜱盾窝面积最大,且盾窝孔数达21~35个.盾窝的发育主要在幼蜱蜕皮阶段及若蜱的吸血和蜕皮阶段,雌蜱盾窝孔径显著大于雄蜱（P<0.01）,成蜱、若蜱和幼蜱的盾窝孔孔径在吸血过程中（交配雌蜱除外）各虫期均无显著变化 （P>0.05）.综合分析成蜱与未成熟蜱盾窝孔径,发现它们之间无显著差异 （P>0.05）,这在一定程度上说明蜱类的盾窝孔径在未成熟期可能已经有了雌雄分化.     

Pathognomonic macular ripples are revealed by polarized infrared retinal imaging

A pathognomonic macular ripple sign has been reported with scanning laser ophthalmoscopy images in patients with foveal hypoplasia, though the optical basis of this sign is presently unknown. Here we present a case series of seven individuals with foveal hypoplasia (based on spectral domain optical coherence tomography). Each patient underwent infrared scanning laser ophthalmoscopy retinal imaging in both eyes, acquired with and without a polarization filter and assessment for a ripple-like effect in the fovea. On imaging, macular ripples were present in all eyes with foveal hypoplasia when using a polarization filter, but not when imaged without the filter. We conclude that the macular ripple sign is an imaging artifact attributable to the unique pattern of phase retardation of the Henle fiber layer in the setting of foveal hypoplasia. By utilizing a polarization filter with retinal photography, this feature can be exploited to promptly identify foveal hypoplasia in settings where OCT is not possible due to nystagmus.     

Active electroreception in Gymnotus omari: Imaging, object discrimination, and early processing of actively generated signals

Weakly electric fishes “electrically illuminate” the environment in two forms: pulse fishes emit a succession of discrete electric discharges while wave fishes emit a continuous wave. These strategies are present in both taxonomic groups of weakly electric fishes, mormyrids and gymnotids. As a consequence one can distinguish four major types of active electrosensory strategies evolving in parallel. Pulse gymnotids have an electrolocating strategy common with pulse mormyrids, but brains of pulse and wave gymnotids are alike. The beating strategy associated to other differences in the electrogenic system and electrosensory responses suggests that similar hardware might work in a different mode for processing actively generated electrosensory images. In this review we summarize our findings in pulse gymnotids’ active electroreception and outline a primary agenda for the next research.     

Ontogenesis of auditory fovea representation in the inferior colliculus of the Sri Lankan rufous horseshoe bat,Rhinolophus rouxi

Summary This report describes the ontogenesis of tonotopy in the inferior colliculus (IC) of the rufous horseshoe bat (Rhinolophus rouxi). Horseshoe bats are deaf at birth, but consistent tonotopy with a low-to-high frequency gradient from dorsolateral to ventromedial develops from the 2nd up to the 5th week. The representation of the auditory fovea is established in ventro-mediocaudal parts of the IC during the 3rd postnatal week (Fig. 3). Then, a narrow frequency band 5 kHz in width, comprising 16% of the bat's auditory range, captures 50–60 vol% of the IC (Fig. 3c). However, foveal tuning is 10–12 kHz (1/3 octave) lower than in adults; foveal tuning in females (65–68 kHz) is 2–3 kHz higher than in males (62–65 kHz). Thereafter, foveal tuning increases by 1–1.5 kHz per day up to the 5th postnatal week, when the adult hearing range is established (Figs. 4, 5). The increase of sensitivity and of tuning sharpness of single units also follows a low-to-high frequency gradient (Fig. 6).Throughout this development the foveal tuning matches the second harmonic of the echolocation pulses vocalised by these young bats. The results confirm the hypothesis of developmental shifts in the frequency-place code for the foveal high frequency representation in the IC.Abbreviations BF best frequency - CF constant frequency - FM frequency modulation - IC inferior colliculus - IHC inner hair cell; - OHC outer hair cell - RR Rhinolophus rouxi