水文气象因子变化对自然海区对虾早期生命的影响

利用渤海湾对虾卵子、幼体和幼虾调查资料，引用相对成活倍数的概念，并选择与对虾早期生命有因果关系的水文气象因子，通过相关分析方法分析讨论了水文气象因子变化对对虾早期生命的影响。结果表明，６￣７月盐差、５月中旬产卵场现场水温和黄河径流对对虾早期生命影响较明显。     

The effect of the host lymphocyte lysosomal system on the developing intracellular Theileria annulata sporozoites

The fate of developing intracellular Theileria annulata sporozoites within bovine peripheral blood lymphocytes (PBL) was investigated in vitro using acid phosphatase ultracytochemistry. The intracellular sporozoites, while they developed into trophozoites, fed, and transformed into schizonts, provoked intense host lysosomal activity as early as 30 min after they were mixed with lymphocytes. Although viable developing trophozoites failed to fuse with lysosomal vesicles, thereby avoiding enzymatic digestion, the dead parasites readily formed 'phagolysosomes', resulting in lysosomal degranulation and trophozoite digestion. Possible factors responsible for the observed lack of lysosomal fusion with viable trophozoites are discussed.     

Factors affecting the capacity of Theileria annulata sporozoites to invade bovine peripheral blood lymphocytes

The number of T. annulata sporozoites invading bovine peripheral blood lymphocytes (PBL) under different conditions (in vitro) was determined. Heat-inactivation of T. annulata sporozoites for 45 min, in a thermostatically controlled, shaking water bath preset and stabilised at 60 degrees C resulted in an almost total lack of invasion of fresh, normal PBL by the sporozoites, indicating that the interiorization process is parasite-effected. The mean number of T. annulata sporozoites interiorization (per 1000 lymphocytes) in cultures set up using sporozoites and PBL, mixed and incubated at 0 degrees C for 1 h in melting ice, was highly significantly reduced (P less than 0.01), indicating the invasion of bovine lymphocytes by T. annulata sporozoites is an active process dependent on active metabolism which is markedly affected by temperature. Pre-treatment of PBL with trypsin significantly reduced the number of invading sporozoites thus incriminating proteins or glycoproteins as constituents of receptors involved in sporozoite-lymphocyte recognition.     

A comparative study of the diseases in cattle caused by Theileria Lawrencei and Theileria Parva. 1. Clinical signs and parasitological observations

A comparison was made between the clinical signs and blood and lymph node parasite levels in cattle reacting to the inoculation of tick-derived stabilates of Theileria lawrencei (TL), and T. parva at high dose (TPH) and low dose (TPL) levels. The TL and TPH infections produced acute diseases with statistically similar tines to death of 13.50 and 14.25 days, respectively, while TPL caused a more protacted but equally fatal disease of 20 days duration. In the TPL group, the local drainage lymph node (LDLN) became enlarged earlier and macroschizonts appeared later than in the TPH group. The characteristics of T. lawrencei infection which differentiated it from T. parva infection were: nervous signs; complete anorexia; low macroschizont index (MSI) levels of up to 5%; and lack of piroplasms. In T. parva groups, the high MSI levels of up to 60%, presence of piroplasms and dysentery were characteristic. In addition, the enlargement of lymph nodes in the TL group persisted to time of death, while in both T. parva infections the initial enlargement was followed by a decrease in size.The 100-fold dose difference between TPH and TPL influenced the times of onset of the majority of clinical signs, most of which occurred later in the TPL group. The MSI levels were 60% in the TPH group and 40% in the TPL group. The piroplasm parasitemia levels reached 5% in the TPH group, and 16% in the TPL group.Theileria lawrencei and T. parva caused diseases with significant differences in clinical manifestations and parasite levels in erythrocytes and lymphocytes. The size of the infecting dose influenced the time of onset of clinical signs as well as the duration of the disease.     

Fine structure and invasive behaviour of the early developmental stages of Theileria annulata in vitro

The interaction, in vitro, between bovine peripheral blood lymphocytes and sporozoites of Theileria annulata (Ankara) was studied by light and electron microscopy. Beginning five minutes following incubation, samples were taken for Giemsa-stained smears and glutaraldehyde-fixed pellets, for light and electron microscopy, respectively. Sporozoites of T. annulata measure an average of 0.9 microns long, 0.8 microns broad and possess a limiting unit membrane, the pellicle; a round-to-ovoid, eccentrically situated, non-chromocentric nucleus; double-membraned, tubular, acristate mitochondria; varying numbers of anisocytic, densely osmiophilic and pleomorphic organelles, the rhoptries which together with the polar ring form the apical complex; and numerous, loosely scattered, electron-dense ribosomal particles. As early as 5 min of incubation, sporozoites had made contact with, and penetrated, lymphocytes. Sporozoites consistently attached to the lymphocyte plasmalemma by their basal end, possibly at specific receptor sites. Apparently only a proportion of lymphocytes (up to 40% and more commonly 10-20%) were susceptible. Two subpopulations of the susceptible lymphocytes were observed; one which appeared to have receptor sites localized on one pole of the plasmalemma and the other subpopulation in which the receptor sites were distributed evenly around the plasmalemmal surface. Within individual susceptible lymphocytes, the number of interiorized sporozoites increased from 1 to 3 at 5-10 min to as many as 15 or more parasites at around 60 min of incubation. Theileria annulata sporozoites were interiorized by the invagination of the host cell plasmalemma which remained intact throughout the process but later fragmented. Within 30 min of interiorization, each sporozoite underwent dedifferentiation by the loss of its rhoptries and transformed into a trophozoite. Around 24 h, the trophozoite, a uninucleate, motile and feeding stage of the parasite, developed into a schizont by an acentric, closed mitosis.     

Ultrastructural characteristics of in vitro parasite-lymphocyte behaviour in invasions with Theileria annulata and Theileria parva

Host-parasite relationships have been studied by electron microscopy using glutaraldehyde-OsO4-fixed pellets of lymphoid cultures infected in vitro by Theileria annulata and T. parva. Intracellular presence of the parasite resulted in a progressive and marked lymphoblastoid transformation. The schizont stage periodically provoked the formation of, and adopted an intimate association with, cytoplasmic annulate lamellae in the interphase cell. Annulate lamellae developed from the outer nuclear membrane of the host cell by a delamination process and were taken into the cytoplasmic matrix of the schizont by phagotrophy through the cytostome. Schizont nuclei themselves were seen to divide at the prometaphase stage of host cell mitosis, the division being characterized by the development of intranuclear spindle microtubules anchored in spindle pole bodies. A hypothesis is propounded that Theileria parasites, consequent on interiorization, provoke the blastoid transformation and the formation of annulate lamellae through the influence of components of their genomic material on host cell deoxyribonucleic acid (DNA) and that the annulate lamellae represent a species of messenger ribonucleic acid (mRNA) and serve as a monitoring device for the schizont, facilitating the accurate timing of the host cell cyclical events.     

Search for interstellar superheavy hydrogen

Models for fundamental physical interactions allow for the existence of stable or nearly stable elementary particles much heavier than the proton. Stellar spectra were searched for a positively charged superheavy particle, X(+), which, with a bound electron, should appear as apparently superheavy neutral hydrogen in the interstellar medium. An upper limit for the abundance of X relative to normal hydrogen in the line of sight toward the bright star gamma Cassiopeiae is 2 x 10(-8).     

Invasion and intracellular development of Theileria annulata sporozoites in lymphoblastoid cell lines already transformed by T. annulata (Hissar), T. annulata (Ankara) and T. parva (Muguga)

Interactions between Theileria annulata sporozoites and lymphoblastoid cell lines already transformed by the Hissar and Ankara strains of T. annulata [T. a. (H) and T.A. (A), respectively] and the Muguga strain of T. parva [T.P. (M)] were studied in vitro. Although sporozoites of the Hissar strain of T. annulata attached to and entered peripheral blood lymphocytes (PBL) and lymphoblastoid cell lines transformed by T. a. (H) and T. a. (A), they neither attached to nor entered the T. p. (M) cell line. Whether the superinfecting T. a. (H) sporozoites developed intracellularly was studied by monitoring daily changes of mean schizont nuclear numbers and by determining electrophoretic mobilities of schizont glucose phosphate isomerase in each cell line using thin-layer starch gel electrophoresis. While the mean schizont nuclear number in freshly-infected PBL underwent a steady increase to the level of those in long standing T. annulata cultures, analysis of variance of similar data in T. a. (H) and T. a. (A) cell lines in which superinfection was demonstrated revealed no significant differences between them and their respective control counterparts, i.e., T. a. (H) and T. a. (A) cultures with no superinfection. Enzyme polymorphism studies showed the formation of uncontaminated species- or strain-specific bands of glucose phosphate isomerase (GPI) isoenzyme activity in the T. p. (M) and in the superinfected T. annulata cell lines.     

Kinematic evidence for an old stellar halo in the Large Magellanic Cloud

The oldest and most metal-poor Milky Way stars form a kinematically hot halo, which motivates the two major formation scenarios for our galaxy: extended hierarchical accretion and rapid collapse. RR Lyrae stars are excellent tracers of old and metal-poor populations. We measured the kinematics of 43 RR Lyrae stars in the inner regions of the nearby Large Magellanic Cloud (LMC) galaxy. The velocity dispersion equals 53 +/- 10 kilometers per second, which indicates that a kinematically hot metal-poor old halo also exists in the LMC. This result suggests that our galaxy and smaller late-type galaxies such as the LMC have similar early formation histories.