Identification of synergistic signals initiating inner ear development

Tissue manipulation experiments in amphibians more than 50 years ago showed that induction of the inner ear requires two signals: a mesodermal signal followed by a neural signal. However, the molecules mediating this process have remained elusive. We present evidence for mesodermal initiation of otic development in higher vertebrates and show that the mesoderm can direct terminal differentiation of the inner ear in rostral ectoderm. Furthermore, we demonstrate the synergistic interactions of the extracellular polypeptide ligands FGF-19 and Wnt-8c as mediators of mesodermal and neural signals, respectively, initiating inner ear development.     

鼓室碘附应用对豚鼠内耳Mg^2＋ATPase活性研究

在豚鼠鼓宝应用碘附以探讨外用消毒药物对内耳损伤的发病机理,实验表明:用药后能致血管纹、柯替氏器毛细胞Mg~(2+)ATPase活性下降。Mg~(2+)ATPase即镁泵,属糖蛋白,定位于线粒体及细胞膜上,反映细胞线粒体需能供能代谢情况。碘附对内耳毒性作用是I~+透入内耳卤化蛋白质,使Mg~(2+)ATPase失活,可引起听功能障碍。     

多层螺旋CT诊断先天性外耳道闭锁的价值

目的探讨多层螺旋CT（MSCT）对先天性外耳道闭锁（CAA）的诊断价值。方法 21例CAA患者采用MSCT扫描,将原始数据进行三维重组。结果 21例患者中共有23耳闭锁,其中骨性闭锁21耳,膜性闭锁2耳;伴外耳道畸形4耳,鼓室发育异常19耳,听小骨畸形9耳,内耳畸形3耳,耳廓结构异常20耳。结论 MSCT可明确显示外耳、中耳、内耳畸形,有助于CAA的临床分型、手术适应证的确定及术式选择。     

斑马鱼中Wnt信号通过调控侧线基板形成影响侧线发育机制

鱼类侧线系统源自胚胎期的侧线基板,侧线基板的特化受到多种信号的综合作用。利用转基因斑马鱼hsp:wnt8a-egfp和hsp:dkk1-egfp,增强或抑制Wnt信号,通过YO-PRO-1染色和毛细胞计数,研究斑马鱼中Wnt信号对侧线系统发育的影响。热激诱导Dkk1过表达后,斑马鱼侧线系统的神经丘不能形成。碱性磷酸酶染色和整体原位杂交结果表明:Wnt信号是神经丘毛细胞前体细胞以及侧线基板标记基因Eya1和Six2b表达所必需的。综上结果:Wnt信号可能通过调控侧线基板形成影响斑马鱼的侧线发育。     

Coevolution of sender and receiver: effect on local mate preferecnce in cricket frogs

Mate recognition in frogs requires congruence of call characters, such as dominant frequency, and properties ofthe auditory system, such as frequency sensitivity of inner ear organs. Two neighboring populations of cricket frogs (Acri crepitans) exhibit statistically significant differences in the dominant frequency of the advertisement call and the frequency to which the basilar papilla of the inner ear is most sensitive. Call frequency and frequency sensitivity are matched within but differ between populations. These characters usually are negatively correlated with body size, and thus their congruence and coevolution often is explained by pleiotropic effects of size. However, within this species call frequency and frequency sensitivity ofthe basilar papilla evolved independent of body size, yielding local mate preferences that could contribute to genetic differentiation among neighboring populations.     

Ouabain and streptomycin: their different loci of action on saccular hair cells in goldfish

Ouabain, when applied to the periotic spaces, that is, to the basal end of the saccular hair cells, suppressed microphonic potentials of the inner ear in goldfish. In contrast, streptomycin produced such an effect only when it was applied directly into the endolymph, that is, to the hair-bearing ends of the hair cells.     

Organic Compounds in Meteorites: They may have formed in the solar nebula, by catalytic reactions of carbon monoxide, hydrogen, and ammonia

Organic compounds in meteorites seem to have formed by catalytic reactions of CO, H2, and NH3 in the solar nebula, at 360 degrees to 400 degrees K and (4 to 10) x 10-6 atm. The onset of these reactions was triggered by the formation of suitable catalysts (magnetite, hydrated silicates) at these temperatures. These reactions may be a source of prebiotic carbon compounds on the inner planets, and interstellar molecules.     

内蒙古绒山羊毛囊形态发生规律

以胚胎龄40~110 d内蒙古二郎山绒山羊胚胎体侧部皮肤为材料,通过石蜡切片、HE染色,研究绒山羊胚胎毛囊形态发生规律。结果显示,内蒙古绒山羊胚胎皮肤初级毛囊形态发生经历毛基板前期、毛基板期、毛芽期、毛钉期和毛囊期5个时期,这5个时期又可根据其形态结构的差异划分为不同的亚期,内蒙古绒山羊胚胎皮肤初级毛囊形态发生与汗腺的发生相伴随;内蒙古绒山羊皮肤初级毛囊形态发生是分批进行的。在胚胎龄40~110 d内蒙古绒山羊胚胎体侧部皮肤未观察到次级毛囊的发生。     

玉米收获期籽粒含水量与主要农艺性状相关分析

以黑龙江省第一积温带10份熟期相近而收获期含水量差异较大的优良自交系为试验材料,采用完全双列杂交设计配制杂交组合,对田间自然脱水速率、苞叶长等农艺性状与玉米收获期籽粒含水量进行遗传相关和通径分析。相关分析表明,田间自然脱水速率与收获期籽粒含水量表现为极显著负相关(R=-0.4508),苞叶长、粒宽等性状与收获期籽粒含水量表现为极显著正相关;通径分析表明,苞叶长、粒宽等性状对收获期含水量的直接通径系数均为正值,穗长、田间自然脱水速率对收获期含水量的直接通径系数为负值。为选育低收获期含水量的玉米品种,应着重选育田间自然脱水速率快、苞叶长较果穗长略短、穗位稍低、轴细、籽粒偏窄及百粒重稍低的基因型。     

Interrelated striated elements in vestibular hair cells of the rat

Unusual fixation procedures revealed a series of interrelated striated organelles in type I and type II vestibular hair cells of the rat; these organelles seemed to be less well developed in cochlear hair cells. The findings suggest that contractile elements may play a role in sensory transduction in the inner ear, particularly in the vestibular system.     

Auditory and vibratory responses in the midbrains of snakes

Airborne sound and substrate vibration each elicit electrical responses below the surface of the tectum in species of three families of snakes. Tones of 50 to 1000 hertz evoke responses independently of substrate vibration. Sensitivity to locally applied sound is present over much of the body surface. This sensitivity is attributed to the auditory nerve, because it is not altered by spinal section but is eliminated by destruction of the inner ear.     

鲜食甜玉米主要性状的灰色关联度、相关及通径分析

以20个甜玉米(Zea mays L.cv.Sweet)杂交组合为对象,对其鲜质量以及株高、穗位高、穗长、秃尖长、穗粗、穗行数、行粒数、茎粗、叶片数、穗上叶数、穗位叶长和穗位叶宽等12个主要农艺性状指标进行了调查,并与鲜质量进行了灰色关联度、相关及通径分析.结果表明,甜玉米植株田间农艺性状与鲜质量相关程度较小;穗粗、行粒数、穗长与鲜质量呈极显著正相关;果穗粗、行粒数、穗长对鲜质量的直接影响较大,穗行数对鲜质量的间接影响较大.认为在高产甜玉米育种中,应重视穗粗和穗长的选择.     

超声波对小麦面筋蛋白结构的影响

【目的】研究超声波对面筋蛋白结构的影响,为超声波处理改善面筋蛋白功能性质提供理论依据。【方法】借助红外光谱、扫描电镜、激光粒径仪了解超声波处理对面筋蛋白二级结构、非共价键、二硫键及显微结构的影响。【结果】超声波处理使面筋蛋白二级结构的α-螺旋结构增加、β-转角结构显著减少,而β-折叠结构则因超声功率不同变化不同;超声波处理破坏了面筋蛋白分子间/内氢键、SS键、疏水键的致密连接,导致面筋蛋白松散的显微结构形成和体积平均粒径的增大。【结论】超声波通过削弱面筋蛋白紧密结构赖以支持的作用力包括SS键、氢键、疏水键,而形成松散的结构。     

玉米主要穗部性状的变异及相关性分析

为了明确玉米主要穗部性状的遗传变异规律,分析重要穗部性状间的相关性。以组合HN4*QN17 自交衍生形成的包括287 个家系的F2：3群体及其相应的亲本作为试验材料,按照随机区组排列进行田间试验。应用Excel2003 和DPS2000 对9 个主要穗部性状数据资料进行变异特性和相关性分析。结果表明,穗部性状呈双向超亲分离,9个穗部性状变异系数的大小两试验点（海南三亚和山东青岛）具有较好一致性,性状变异系数的大小顺序为秃尖长>穗粒重>行粒数>穗长>百粒重>穗行数>穗轴粗>穗粗>出籽率;除秃尖长外,穗粒重与其他7个性状均达到极显著的正相关关系,穗粒重与各性状的相关性大小顺序依次为行粒数>穗长>穗粗>百粒重>穗轴粗>出籽率>穗行数。说明秃尖长、穗粒重、行粒数、尧穗长性状变异系数大,在分离世代中有较广泛的选择空间;秃尖长与穗长、穗轴粗与穗粗性状间呈显著正相关性,在育种实践中同步改良这些性状有一定难度;穗行数与行粒数、穗行数与穗粗性状间的显著正相关性,在育种中同步提高这些有利性状是可行的。穗部性状间的变异规律和关联性可为该组合二环系选育中性状的取舍提供一定理论参考。     

Penetration,adhesion, and fusion in mammalian sperm-egg interaction

Fertilization is the sum of the cellular mechanisms that pass the genome from one generation to the next and initiate development of a new organism. A typical, ovulated mammalian egg is enclosed by two layers: an outer layer of approximately 5000 cumulus cells and an inner, thick extracellular matrix, the zona pellucida. To reach the egg plasma membrane, sperm must penetrate both layers in steps requiring sperm motility, sperm surface enzymes, and probably sperm-secreted enzymes. Sperm also bind transiently to the egg zona pellucida and the egg plasma membrane and then fuse. Signaling in the sperm is induced by sperm adhesion to the zona pellucida, and signaling in the egg by gamete fusion. The gamete molecules and molecular interactions with essential roles in these events are gradually being discovered.     

中粳稻分蘖穗率与苗质,秧苗密度和群体质量关系的研究

研究了中粳稻不同分蘖穗率群体与秧苗素质、秧苗密度、茎蘖动态、齐穗期群体质量和稻谷产量的关系。试验结果表明,分蘖穗率与秧苗密度。大田穴苗和最高茎蘖数呈显著负相关,一苗质、分成穗率和齐期的比叶重、粒叶比等群体质量指标均呈显著正相关,提高大田分蘖穗率显著提高穗谷重、谷草比、经济系数和经济产量。在保持秧大田比一致的条件下,培育稀播壮秧,减少大田穴苗数,提高分蘖穗率,建立合理的群体结构,提高群体质量,是水稻     

Developmental biology. Rocks that roll zebrafish

The vestibular organs of the inner ear of higher vertebrates control balance, and their counterparts in fish control both balance and hearing. Essential to the operation of these sensory organs are the biomineralized structures--otoconia in higher vertebrates or otoliths in fish--that deflect the sensory hair bundles situated beneath them. In her Perspective, Fekete explores the fascinating world of otolith biomineralization in zebrafish; revealing the importance of a protein called Starmaker for coordinating the shape and type of crystal in fish otoliths ( S?llner et al.).     

Shark pit organs: enhancement of mechanosensitivity by potassium ions

The mandibular pit organs of pelagic sharks, which respond sensitively to monovalent cations, often show neural discharges synchronized with respiratory gill movement. The mechanosensitivity of the organs is remarkably enhanced by application of potassium ions on the same end organ, respiratory movement remaining constant. In view of their michanosensitivity to an incr-ease of potassium ions in the cell environment, as well as their chemosensitivity,the pit organs of sarks, rather than the canal organs which have no chemosensitivity, may be designated as a better model of the inner ear of higher animals.     

Steroid-dependent auditory plasticity leads to adaptive coupling of sender and receiver

For seasonally breeding vertebrates, reproductive cycling is often coupled with changes in vocalizations that function in courtship and territoriality. Less is known about changes in auditory sensitivity to those vocalizations. Here, we show that nonreproductive female midshipman fish treated with either testosterone or 17beta-estradiol exhibit an increase in the degree of temporal encoding of the frequency content of male vocalizations by the inner ear that mimics the reproductive female's auditory phenotype. This sensory plasticity provides an adaptable mechanism that enhances coupling between sender and receiver in vocal communication.     

广汉县小麦绵阳11号在不同产量水平下穗数穗重的作用

<正> 小麦亩产量是亩穗数和单穗重的乘积,穗重又由千粒重和穗粒数决定。关于产量因素与产量之间的数量关系、国内外已有许多报道,如张作仿等研究认为,穗粒数对产量的影响最大,有效穗次之,粒重最小。Sinha G·C·P。则认为,不同品种中,各产量因素对产量作用的大小不同,但似乎倾向于穗粒数和千粒重与产量直接相关。然而,对一个特定的品