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41.
Isopropylidenation of lactose with 2,2-dimethoxypropane in the presence ofp-toluenesulfonic acid gave two products, which were identified by1H- and13C-NMR as 2,35,63,4-tri-O-isopropylidenelactose dimethyl acetal (1) and its 6-O-(2-methoxy)-isopropyl derivative (2). These products were used for the synthesis of 2-O-methyllactose (7), 2,6-di-O-methyllactose (9) and 2-O-benzyllactose (13). 相似文献
42.
43.
T K Kobayashi T Yamaki E Yoshino S Terawaki K Tara K Nishida I Sawaragi 《Acta cytologica》1983,27(3):281-284
A case of meningitis due to Acinetobacter calcoaceticus occurred after neurosurgery. The cerebrospinal fluid cytology showed intracellular diplococci that strongly resembled Neisseria meningitidis. However, subsequent bacteriologic studies revealed a bacterium identical to A. calcoaceticus. It is of practical importance for cytology laboratories to recognize this diplococcal form of organism. 相似文献
44.
The distribution and abundance of the lysosomal enzyme markers, acid phosphatase (AP), peroxidase (PO), and nonspecific esterase (NE), within circulating blood cells (hemocytes) were examined in a schistosome-susceptible (PR albino M-line) and a resistant (10-R2) strain of Biomphalaria glabrata during the course of infection with Schistosoma mansoni. The dynamics of serum (cell-free hemolymph) AP activities and total hemocyte numbers in infected snails also were investigated. Hemocyte subpopulations, as determined by these enzyme markers, responded differently to parasite infection between snail strains. Generally, the hemocyte subpopulations within PR albino snails remained largely unchanged, whereas the same subpopulations in 10-R2 snails fluctuated considerably. The distribution of AP in the hemocytes of 10-R2 snails decreased by 1 hr postexposure (PE) to the parasite and remained low through 12 hr before increasing to control values at 24 hr and 2 wk PE. In comparison, PO activity increased by 1 hr PE and peaked at 12 hr before dropping to 0 hr values by 2 wk PE. The NE activity exhibited still another pattern with the percentage of NE-positive cells decreasing from 0 to 12 hr PE followed by a recovery to 0-hr values by 24 hr. The abundance of these hemocyte enzymes followed a similar pattern to that of their distribution, although some differences were observed. Serum AP values varied little in PR albino snails except for a significant increase at 2 wk PE, indicating a possible response to tissue damage resulting from migrating daughter sporocysts.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
45.
46.
Summary Spermatozoa from fertile and infertile human ejaculates were observed under the scanning electron microscope. A parallel study of sections was performed by transmission electron microscope.The normal head shows under the scanning electron microscope vesicular elevations in the region of the acrosome and a smooth and rigid appearance corresponding to the postnuclear cap whose occurrence is confirmed under the transmission electron microscope. Immediately anterior to this cap a shallow furrow transverses the head. Duplicated, unusually large or small and deformed heads are found under the scanning electron microscope. Most of these abnormal heads show no surface structure suggesting an acrosome.The neck and middle piece are occasionally, though frequently in abnormal spermatozoa, covered by a cytoplasmic droplet. Otherwise, the mitochondrial sheath is recognized under the scanning electron microscope as a beaded thickening in the middle piece. The lack of mitochondria is manifested by a smooth middle piece thinner than the principal portion. Transmission electron microscopy of sections reveals various types of anomalies in the number of cores, core filaments and mitochondria embedded in the cytoplasmic droplets.Abnormalities in the principal portion of the tail such as duplication, unusual thickness and length are shown under the scanning electron microscope.The investigation indicates that scanning electron microscopy is suited for the clinical as well as cytological examination of human ejaculate spermatozoa. 相似文献
47.
Masayuki Miyoshi 《Cell and tissue research》1970,104(2):213-230
Summary The fine structure of the mesonephric kidney of the lamprey, Entosphenus japonicus Martens, has been investigated with the electron microscope and discussed from the viewpoint of comparative morphology of the mesonephros.The structure of the capillary wall of the glomerulus essentially coincides with that of higher vertebrates, though its basement membrane is remarkably thick (300–400 m) because of a dense accumulation of fibrillar material between the endothelium and the basal lamina of epithelial cell. No obvious fenestration of the endothelial cell has been observed in the glomerulus or capillaries in any part of this organ.The kidney tubule is divided into three segments: 1. neck segment composed of ciliated cells with numerous mitochondria and glycogen particles, 2. proximal tubule composed of brush bordered cells provided with extensive pinocytotic vesicles and lysosomal granules in the apical cytoplasm and with lamellar membranes in the basal, and 3. distal tubule characterized by cells which, with their abundant mitochondria and branched tubular endoplasmic reticulum (about 500 Å diameter) with a central core, closely resemble the chloride cells in the gill filament of some teleosts. The possibility that the lamellar membranes in the proximal tubule cells correspond to basal infoldings is discussed.The extensive development of the tubular reticulum and of the mitochondria in the distal tubule cells is believed to reflect the active absorption of urine chloride in the urinary tubule of lamprey mesonephric kidney evidenced by physiologists. The proximal tubule is suggested to take a part also in the urinary transport of water and ions, as the lamellar membranes found in the cells of this portion likely correspond to the basal infoldings in more advanced forms of the kidney.The epithelial cells of the ureteric duct are characterized by granules suggesting a mucous secretion. No fine structure implying an absorptive activity in this duct has been observed. 相似文献
48.
49.
To evaluate the influence of overwintering individuals of zooplankton on spring zooplankton communities, the dynamics of zooplankton
communities with or without overwintering individuals were observed in experimental ponds from fall to spring. An insecticide,
carbaryl, was used to regulate the overwintering individuals. In ponds which received insecticide applications in November
or January, all cladoceran and rotiferan species were eliminated by the treatments and did not reappear until late March or
early April, even when the chemical disappeared rapidly. The low water temperature may delayed the establishment of the populations
from resting eggs. In these ponds, populations of various cladoceran and rotiferan species, which seemed to be originated
from resting eggs, were built up in the spring. In control ponds,Daphnia ambigua orD. longispina overwintered as juveniles and adults and established a large spring population earlier than other cladocerans and rotifers
overwintering as resting eggs. The latter zooplankters did not increase in the spring probably because their growth was suppressed
by the precedingDaphnia species through competition. In nature, even if the number of overwintering individuals is small, they may have a potential
to build up a large population earlier than the individuals hatching from resting eggs. As a result, the species which have
overwintered as individuals seem to predominate in the spring and have a large influence on the spring zooplankton community. 相似文献
50.
Mariyo F. Watanabe Ken-Ichi Harada Kennji Matsuura Masayuki Watanabe Makoto Suzuki 《Journal of applied phycology》1989,1(2):161-165
Changes in the content of cyclic heptapeptide hepatotoxins called microcystins were investigated during batch culture of two
Microcystis species using high performance liquid chromatography. After adsorption to ODS-silica gel cartridges and elution with methanol,
the toxins were analyzed and quantified by HPLC. 35 μg per 100 mg dry cells of microcystin-RR, 34 μg of -YR and 43 μg of -LR
were present at the beginning of the exponential growth phase of M. viridis. Microcystin-RR increased markedly towards the end of the exponential phase with the maximum content of 112 μg per 100 mg
cells was measured at the late stage of the exponential phase. A remarkable increase of microcystin-YR from 130 μg per 100
mg cells to 1020 μg was observed during the exponential phase of a highly toxic strain of M. aeruginosa. However no clear differences were found in the pattern of change among the three toxins during the growth course. 相似文献