Comparative photosynthetic studies of Ecklonia cava (Laminariales,Phaeophyta) bladelets with and without zoosporangial sori

Photosynthetic rates were compared between Ecklonia cava bladelets with and without zoosporangial sori sampled from the subtidal zone (about 5 m deep) in Nabeta Bay, Shimoda, Japan. Photosynthetic rates of bladelets were lower in the sorus portion than in the non-sorus portion on the basis of area, dry weight and chlorophyll a. Respiration rates were higher in the sorus portion than in the non-sorus portion on the basis of area and chlorophyll a, whereas they were almost the same on a dry weight basis. The differences were mainly due to a large difference in dry weight per unit bladelet area between the sorus and the non-sorus portion. Light compensation points were higher in the sorus portion than in the non-sorus portion.     

小煤炱科子囊壳超微结构研究

用扫描电镜对小煤炱科Meliolaceae的美座附丝壳Appendiculella calotroma(Desm.)Hoehnel和莫勒针壳炱Irenopsis molleriana(Wint.)Stev.的子囊壳进行观察的结果,发现它们的子囊壳都有一个小孔口,孔口周围有2～4层小圆柱形至椭圆形细胞;它们的子囊壳表面细胞呈疣状或乳突状,具纵向沟纹。其中美座附丝壳还有具横条纹的蠕虫状附属物,莫勒针壳炱有光滑的子囊壳刚毛。子囊壳表面孔口的发现为小煤炱目Meliolales的确立提供了直接的证据。     

Developmentally regulated proteases in Allomyces arbuscula

A calcium-requiring neutral protease has been detected in the vegetative mycelia of Allomyces arbuscula. The half maximum activation of the enzyme required 0.7 mM and 2.8 mM Ca²⁺ in the crude and partially-purified preparation, respectively. Coinciding with differentiation of zoosporangia, there is a massive induction of another neutral protease which does not require Ca²⁺ for its activity and is of the serine type.     

Vapor Fixation of Intractable Fungal Cells for Simple and Versatile Scanning Electron Microscopy

Imaging of exudation of conidia from fruiting bodies by scanning electron microscopy is challenging because of the difficulty in achieving specimen fixation that enables conidia to be immobilized from fruiting bodies. Conidia in chains borne on conidiophores are readily dissipated on coming in contact with liquid fixatives before fixation becomes effective. Two phialide‐forming fungi including Aspergillus and Penicillium species, and a pycnidium‐forming fungus Fusicoccum species were subjected to a vapor fixation procedure for scanning electron microscopy rather than conventional immersion fixation procedures. The intractable fungi were exposed to the vapor of 2% glutaraldehyde and 2% osmium tetroxide each for at least 2 h, subsequently followed by gold coating. Through the vapor fixation, excellent retention of conidial chains in phialides was achieved in this study. It appeared that conidial masses from pycnidia were usually held together in globose to oval drops. The simple vapor fixation procedure for preserving delicate fungal cells could be widely used for routine applications to facilitate morphological characterization of diverse plant pathogenic fungi as they are in ex planta ecological niches during the saprophytic phase as well as in host parts during the parasitic phase.     

Body size in a pollinating fig wasp and implications for stability in a fig‐pollinator mutualism

The fig–fig pollinator association is a classic case of an obligate mutualism. Fig‐pollinating wasps often have to fly long distances from their natal syconia to a receptive syconium and then must enter the narrow ostiole of the syconium to reproduce. Large wasps are expected to have a greater chance of reaching a receptive syconium. In this study, we tested this hypothesis and then examined whether the ostiole selectively prevented larger pollinators from entering the syconial cavity. In Xishuangbanna, China, Ceratosolen solmsi marchali Mayr (Hymenoptera: Agaonidae) pollinates the dioecious syconia of Ficus hispida L. (Moraceae). The body size of newly emerged wasps and wasps arriving at receptive syconia were compared. Wasps arriving at receptive syconia were significantly larger than newly emerged wasps. We also compared the size of wasps trapped in the ostiole with those in the cavity. Wasps trapped in the ostiole were significantly larger than those in the syconial cavity. Thus, in the case of F. hispida, large wasps were more likely to reach receptive syconia, but the ostiole limited maximum fig wasp size. This indicates that the ostiole, as a selective filter to pollinators, stabilizes pollinator size. Hence, it helps to maintain stability in the fig–fig pollinator mutualism.