Leaf micromorphology inAgathis and its taxonomic implications

This study surveys the micromorphological surface structure of the leaves of the conifer genusAgathis (Araucariaceae) from throughout the range of the genus (Malaysia to New Zealand and Fiji) as seen with the scanning electron microscope. These data confirm that the vegetative parts ofAgathis are taxonomically highly conservative, but suggest the Melanesian and New Zealand elements to be distinctive from those of the rest of the genus, and from one another. Conclusions are compared with those that have been derived from studies based on other characters.     

Quantifying Single Microvessel Permeability in Isolated Blood-perfused Rat Lung Preparation

The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement.     

Photosynthesis and water relations and the role of anatomy in Umbilicariaceae (lichenes) from Central Spain

Summary The response of net photosynthesis and dark respiration in eight species of Umbilicariaceae (lichenes) to temperature (-5, 0, 5, 10, 15, 20, 25, 30°C) and irradiance (55, 110, 220, 400, 620 mol photons m^-2 s^-1 PAR) was studied. The samples were collected in montane and alpine localities of the Spanish Sistema Central. The species differed widely in their net photosynthetic rates. The optimal temperature for net photosynthesis in alpine species was significantly lower than in montane species. Montane species were more photophytic than alpine ones. Water saturation and water loss rate were dependent on morphology and particularly anatomy of the thallus. The physiological and structural data are useful in the interpretation of the ecology and altitudinal distribution of the Umbilicariaceae. No adaptation could be linked to particularities of the mediterranean climate.     

赤(瓜包)亚族植物叶片中脉的比较解剖

本文对赤(瓜包)属(Thladiantha Bunge)、白兼果属(Baijiana A.M.Lu et J.Q.Li)和苦瓜属(Momordica L.)共11种植物叶片中脉进行了比较解剖学研究。除苦瓜属一种外,其余10种的叶片中脉解剖学资料均为首次报道。分析结果表明:叶片中脉维管束的数目以及排列方式具有分类学意义,而种间和种内维管束数目的减少,在一定程度上反映出植物迁移和演化的方向。     

Inhibition of macrophage DNA synthesis by immunomodulators. II. Characterization of the suppression by muramyl dipeptide or lipopolysaccharide [3H]thymidine incorporation into macrophages

Guinea pig peritoneal exudate macrophages actively incorporated [3H]thymidine into trichloroacetic acid-insoluble fraction in vitro. The incorporation of [3H]thymidine was almost completely inhibited by aphidicolin, an inhibitor of DNA polymerase alpha and an autoradiograph showed heavy labeling in nuclei of 15% of macrophage populations. These results indicate that the observed thymidine incorporation was due to a nuclear DNA synthesis. The [3H]thymidine incorporation was markedly suppressed when macrophages were activated by immunoadjuvants such as muramyl dipeptide (MDP) or bacterial lipopolysaccharide (LPS). The suppression of [3H]thymidine incorporation by MDP was neither due to the decrease in thymidine transport through the cell membrane, nor due to dilution by newly synthesized "cold" thymidine. An autoradiograph revealed that MDP markedly decreased the number of macrophages the nuclei of which were labeled by [3H]thymidine. These results suggest that the suppression of [3H]thymidine incorporation by the immunoadjuvants reflects a true inhibition of DNA synthesis. The inhibition of DNA synthesis by MDP was also observed in vivo. Further, it was strongly suggested that the inhibition was not caused by some mediators, such as prostaglandin E2, released from macrophages stimulated by the immunoadjuvants but caused by a direct triggering of the adjuvants at least at the early stage of activation. Cyclic AMP appears to be involved in the inhibitory reaction.     

Polysome structure in sea urchin eggs and embryos: an electron microscopic analysis

Primary cultures of cardiac myocytes from newborn normal and genetically cardiomyopathic (strain UM-X7.1) hamsters were analyzed by electron microscopy and immunofluorescent staining for myosin, actin, tropomyosin, and alpha-actinin. Antibody staining of these contractile proteins demonstrates that both normal and cardiomyopathic (CM) myocytes contain prominent myofibrils after 3 days in culture, although the CM myofibrils are disarrayed and not aligned as those in normal cells. The disarray becomes even more pronounced in CM cells after 5 days in culture. The immunofluorescent staining patterns of individual myofibrils in normal and CM cells were similar for myosin, actin, and tropomyosin. However, alpha-actinin staining reveals that the CM myofibrils have abnormally wide and irregularly shaped Z bands. Electron microscopy confirms the irregular Z-band appearance as well as the myofibril disarray. Thus, CM cardiomyocytes clearly show an aberrant pattern of myofibril structure and organization in culture.     

耳河螺生殖器官和精子的形态学研究

耳河螺「Ｒｉｖｕｌａｒｉａ ａｕｒｉｃｕｌａｔａ （Ｍａｒｔｅｎｓ）」为雌雄异体。雄性生殖器官由精巢,输精小管,贮精囊,输精管,前列腺和阴茎组成。精巢内有精子,精子有典型精子和非典型精子两种。扫描电镜下,典型精子头部呈螺旋状,尾端只有一根较粗壮;非典型精子头部和中部为棒状,尾部呈扫帚状,由８－１５根鞭毛组成。     

Relictual vegetative anatomical characters in Cactaceae: the genusPereskia

The genusPereskia, which contains numerous morphological features considered relictual in the Cactaceae, has numerous anatomical features that we consider to be relictual also. These were studied to establish a basis for determining the ways that morphogenic mechanisms and anatomical characters diversified as the family evolved. ThesePereskia features may be relictual in the family: epidermis predominantly unistratose and lacking crystals; hypodermis absent or of about three layers of weakly collenchymatous cells with druses; cortex thin and predominantly parenchyma with druses and mucilage cells but lacking cortical bundles; secondary phloem without early differentiation of sclerenchyma but with secondary sclereids developing later, either idioblastically or in clusters; ergastic substances lacking from old secondary phloem; wood with a matrix of libriform fibers (mostly septate and nucleate), scanty paratracheal parenchyma, vessels solitary or in small clusters, perforations simple, pitting circular, oval or very broad; wide-band tracheids absent; ray cells slightly thick-walled, lignified, upright, isodiametric or procumbent; all primary rays narrow; pith without medullary bundles; leaves lacking hypodermis, with only weak development of palisade mesophyll; veins of four orders, strongly distinct in size, none with fibers; vessels in leaves narrower than those in stems.     

Sink anatomy in relation to solute movement in rice (Oryza sativa L.): A summary of findings

The results of studies on assimilate and water transport in the developing caryopsis of rice are summarised. Evidence is presented for a symplastic movement of solutes as far as the aleurone layer. However, transport into the apoplast at the nucellus/aleurone interface appears to be a necessary step due to the absence of plasmodesmata at this site. It is suggested that water leaves the caryopsis during grain filling by the isolated cell walls of the pigment strand, the suberised walls of these cells functioning to isolate the apoplast from the symplast and thereby allowing opposing fluxes of water and assimilates to occur in the dorsal region of the grain.