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The number of somatic kineties in Pelagostrobilidium ranges from 4 to 6 according to the present state of knowledge. This study investigates Pelagostrobilidium liui n. sp. using live observation, protargol stain, and small subunit rDNA data sequencing. Pelagostrobilidium liui n. sp. is characterized by having a spherical‐shaped body, four somatic kineties, with kinety 2 spiraled around the left side of body, about six elongated external membranelles, and invariably no buccal membranelle. It differs from its most similar congener, Pelagostrobilidium minutum Liu et al., 2012 , in (i) cell shape; (ii) macronucleus width; (iii) oral apparatus; (iv) anterior orientation of kinety 2; (v) location where kinety 2 commences; (vi) arrangement of kinety 1; (vii) distance between the anterior cell end and the locations where kineties commence; and (viii) the presence of 12 different bases (including two deletions) in the small subunit rDNA sequences. The diagnosis of P. minutum Liu et al., 2012 is also improved to include the following new characteristics: invariably four somatic kineties; kineties 2 and 4 alone commence at the same level; kinety 2 originates from right anterior cell half on ventral side, extends sinistrally posteriorly, over kinety 1, around left posterior region, terminates near posterior cell end on dorsal side; kinety 1 commences below anterior third of kinety 2.  相似文献   
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《Palaeoworld》2015,24(3):251-262
The Paleo-Mesoproterozoic Ruyang Group of North China hosts early eukaryotic fossils such as Dictyosphaera, Shuiyousphaeridium, and Valeria, and thus offers valuable insights into the early evolution of single-celled eukaryotic life. In this paper, we report several additional forms of organic-walled microfossils from the Ruyang Group, including Plicatidium latum, Spiromorpha sp., and an unnamed form. V. lophostriata from the Ruyang Group is investigated using transmitted light microscopy, scanning electron microscopy, transmission electron microscopy, and biomechanical analysis. V. lophostriata is reconstructed as a spherical vesicle with two hemispherical halves bearing concentric striations resembling latitudinal circles. The formation of striations could be explained using the Belousov-Zhabotinsky reaction model or the Turing reaction-diffusion model. A biomechanical analysis using the thin-walled spherical pressure vessel model suggests that the concentric striations of V. lophostriata may have functioned as a mechanism to guide biologically programmed excystment through medial split. Our analysis provides essential paleontological data to better understand the functional biology and life cycles of early eukaryotes such as Valeria.  相似文献   
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Herein, we provide external and internal morphological data of Scinax skuki tadpoles from its type locality. The benthic tadpole of S. skuki has eyes and nostrils positioned dorsally, vent tube dextral and reaching the free margin of the ventral fin, oral disk ventral with posterior margin concave when partially closed, labial tooth row formula 2/3, and the presence of nonpigmented spurs behind the lower jaw. These characters, together with the absence of a tectum parietale, and the shapes of the pars articularis quadrati and suprarostral, are useful for species identification and may be informative for systematic purposes.  相似文献   
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The shape of the human acetabular cup was commonly represented as a hemisphere, but different geometries and patient-specific shapes have been recently proposed in the literature. Our aim was to test the limits of the sphericity assumption by comparing three different parameterisations, namely the sphere, the ellipsoid and the rotational conchoid. Models of hip surfaces, reconstructed from CT scans taken from Caucasian race cadavers and patients, were automatically processed to extract the acetabular surface. Two separate analyses were carried out on the overall acetabular shape, including both the acetabular fossa and the lunate surface (case A) and acetabular cup represented by the lunate surface only (case B). Nonlinear gradient-based and evolutionary computation approaches were implemented for the fitting process. Minor differences from the three idealised geometries were detected (median values of the fitting errors < 1 mm). Nonetheless, the sphere fitting was found to be statistically different from both the ellipsoid (p < 2.50e ? 10) and the conchoid (p < 1.07e ? 09), whereas no statistical difference was detected between the ellipsoid and the conchoid for case A. Significance of the difference between ellipsoid and sphere (p < 4.55e ? 12) and between conchoid and sphere (p < 1.93e ? 11) was found for case B as well. Interestingly, for case B statistical difference was detected between the ellipsoid and the conchoid. In conclusion, we synthesise that the morphology of the overall acetabular cup can be parameterised both with an ellipsoid shape and with a conchoid shape as well with superior quality than the simple sphere. Differently, if one considers just the lunate surface, better fitting results are expected when using the ellipsoid.  相似文献   
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Correlation between spermathecal morphology and mating systems in spiders   总被引:2,自引:0,他引:2  
This study tested predictions regarding male mating preferences which were based on some aspects of female reproductive morphology which may influence sperm precedence patterns in six species of spiders. Males of two species, whose 'conduit' spermathecal design has been associated in previous studies with first male sperm precedence, showed the predicted preference for associating with immature females about to moult to maturity rather than mature females. Those of a third species, however, associated indiscriminately with mature and penultimate instar females. As predicted, males of three other species with 'cul-de-sac' spermathecal morphology did not associate preferentially with immature females. Immature females were avoided in two of the species, but not in the third. One of the species with cul-de-sac spermathecae showed, as predicted, lack of a strong first male advantage in sperm precedence. These data give only limited confirmation of the predictions.  相似文献   
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Morphological data and results from scanning electron microscopy of seeds and pollen show thatNormania Lowe [syn.Solanum L. subg.Potatoe (G. Don)D'Arcy sect.Normania (Lowe)Bitter] (Solanaceae: Solaneae) should be considered as a distinct genus fromSolanum L. It has two species, one restricted to the island of Madeira [Normania triphylla (Lowe)Lowe] and the other to Tenerife and Gran Canaria [Normania nava (Webb & Berthel.)Franc.-Ort. & R. N. Lester]. These species are extremely rare and had not been found for about 100 years, untilN. nava was rediscovered in two different localities in Tenerife in 1973 and 1982.Normania triphylla was reported in two different places from northern Madeira in 1991. Both species have the highest conservation priority in the Macaronesian region.  相似文献   
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近年来,分子标记和显微光学成像技术的系列突破,使得单细胞分辨的全脑尺度神经群落成像成为现实.然而,现有神经元形态重建工具的发展速度远远滞后于海量数据的产生速度,难以满足现阶段成像数据的分析需求.在此背景下,我们首先分析了神经元形态重建工具发展滞后的原因,简述现有半自动和全自动神经元形态重建工具的特点和最新发展,并结合现有工具的特点分析其向高通量、高准确度重建工具发展时面临的挑战.最后,我们对未来形态重建工具的发展趋势及应用前景做出展望.  相似文献   
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