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Ke Zhou, Ming Li and Wenting Liang

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Ke Zhou, Shan Ouyang and Jiangyuan Fu

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ZHOU Ke, ZHANG Huicong, Josef Baum and CHEN Wei

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KE-FENG FANG, MENG-XIANG SUN, ERHARD KRANZ and CHANG ZHOU

The interaction between lectins and their specific binding sites is believed to play a critical role in fertilization in animals and some lower plants. However, for higher plants there is no information on lectins or their binding sites related to female gametes and fertilization. The present work was designed as a first attempt to reveal the general pattern of lectin binding site distribution on the surface of female cells, namely egg cells, central cells, and synergids of Torenia fournieri and, especially, to investigate the possible effects of cell isolation procedure on the distribution of lectin binding sites. Therefore, concanavalin A (Con A) and wheat germ agglutinin (WAG) binding sites on the surface of both in vitro and in situ living female cells were localized by using fluorescein isothiocyanate (FITC) conjugated Con A and WGA as probes. We demonstrated that enzymatic treatment and isolation procedures did not notably modify the surface character of the female cells and the distribution of Con A and WGA binding sites. It was also found that Con A binding sites were distributed differently on the surface of the female cells, with the strongest fluorescent signal on central cells and the weakest on egg cells. Calcium could greatly enhance the binding of Con A to the cell surface. A polar distribution pattern of Con A binding sites in embryo sacs was observed. The binding sites were obviously densest at the filiform apparatus of the synergids. The basic pattern of WGA binding site distribution was similar to that of Con A's. However, the fluorescent signal of WGA was much weaker than that of Con A and fluorescent patches were usually found on the cell surface.

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Lei Xiong, Xiao-san Li, Ling Wang, Ke Zhou and Liu-wang Nie

Abstract

The Pig-nosed Turtle Carettochelys insculpta (Testudines; Cryptodira; Carettochelyidae) is the sole living representative of the Carettochelyidae. The phylogenetic position of C. insculpta within Testudines has not yet been determined unequivocally. To address this issue, we sequenced the whole mitochondrial DNA (mtDNA) of C. insculpta using the long-and-accurate PCR (LA-PCR) method. The results show that the length of C. insculpta mtDNA is 16 439 bp and its structure is conserved compared to those of other turtles and other vertebrates except the NADH4 gene beginning with an ATC start codon. The 3′-side of the control region in mtDNA has two tandem repeat motifs, each consisting of nine 5′-CA-3′ units and sixteen 5′-AT-3′ units. To assess the phylogenetic position of C. insculpta, Maximum parsimony (MP), Maximum likelihood (ML) and Bayesian (BI) analyses were conducted based on complete mtDNA from 22 taxa. MP analyses robustly supported that the earliest phylogenetic tree splits separated into three basal branches: the Pelomedusidae (Pelomedusa subrufa), the Carettochelyidae (C. insculpta) and an assemblage of 18 cryptodiran turtle species; while ML and BI analyses suggested that Carettochelyidae and Trionychidae formed a clade, and that this clade was the sister taxon to all other cryptodiran turtles.