鸡疟原虫孢子体超微结构的观察

埃及伊蚊感染鸡疟原虫（Plasmodium gallinaceum）18天后解剖,电镜下观察唾液腺内孢子体的形态。孢子体长7μm、宽0.8μm;复合膜由一层外膜、二层内膜及膜下微管组成。发达的膜下微管与孢子体重要的运动功能有关。细胞核约位于正中。胞质较均一,有时有空泡存在,胞质中有散在核糖体,未观察到内质网。孢子体有胞口。发达的棒状体及众多的微线体,可能与孢子体需侵入媒介唾液腺细胞、尔后再侵入鸟类宿主中胚层细胞有关。因而,任何作用于棒状体、微线体并导致其结构及功能变化的药物,都将影响甚至阻断孢子体对宿主细胞的入侵,这就为疟疾的药物预防提供重要理论依据。     

Sequence comparison of 'states' of a1-m1 suggests a model of Spm (En) action

Two states of the a1-m1 allele featuring different phenotypes in the absence as well as in the presence of Spm or En have been cloned and sequenced.. The insertion site and orientation of the Inhibitor (I) element within the two alleles is identical. The sizes of the I elements differ, being 2.2 kb in state 6078 and 789 bp in state 5719A-1. The internal deletion in state 5719A-1 affects sequences within one side of the terminal inverted repeats of the I element. This alteration can be correlated with the decreased response of this state to the Mutator function of Spm. A model for the interaction between Spm (En)-encoded functions and the receptor element is discussed explaining the phenotypic differences between the states of the locus.     

Plasma concentrations of arginine vasotocin, prolactin, aldosterone and corticosterone in relation to oviposition and dietary NaCl in the domestic fowl

The osmolality and concentrations of Na, K, Cl and the hormones arginine vasotocin (AVT), prolactin, aldosterone and corticosterone were measured in plasma as functions of time in relation to oviposition, changing NaCl content of the diet, and feeding-inanition. AVT was significantly increased immediately after oviposition (but not during the hour before) with a calculated average value of 38.0 +/- 4.1 pg/ml at oviposition. A moderate increase in concentrations of prolactin and corticosterone were observed immediately after oviposition. Oviposition was not associated with detectable changes in plasma osmolality (and electrolyte concentrations) nor with the concentration of aldosterone. After a sudden change from a high NaCl diet to a low NaCl diet the plasma osmolality and concentrations of NaCl, AVT and prolactin reached new stable levels in 24 hr, whereas the plasma aldosterone concentration required more than 4 days to reach a steady level. After resalination plasma aldosterone was suppressed in less than 8 hr. Both osmolality and concentrations of AVT and prolactin showed transient overshoots during the first 24 hr. NaCl depletion resulted in a transient increase of corticosterone.     

Crosslinking of chromosomal antigen common in human tumors to DNA by cis-diamminedichloroplatinum (II)

The antisera specific for dehistonized Hela cell chromatin were obtained by injecting rabbits or goats. Treatment of chromatin with cis-DDP crosslinked the active proteins to DNA thus preventing dissociation of the proteins in a high salt environment.Immunochemical staining of electrophoretically separated chromosomal proteins transferred to nitrocellulose sheets revealed that cis-DDP among others crosslinked the protein with m.w. of about 81 000. This protein is the only major protein antigen presented in several human tumors and absent in normal human tissues.     

Simultaneous ultrastructural demonstration of retrogradely transported horseradish peroxidase and choline acetyltransferase immunoreactivity

In order to study the synaptic connections of neurons identified by their projection target and neurotransmitter content, we have adapted a method of combining retrograde tracing of horseradish peroxidase (HRP) and immunocytochemistry at the electron microscopic level. HRP was injected into the rat amygdala. Sections from the rostral forebrain were processed according to the 3,3'-diaminobenzidine/glucose oxidase reaction followed by choline acetyltransferase (ChAT) localization. Neurons in the ventral pallidum which contained both the diffuse immunoperoxidase reaction product (ChAT) and large electron dense bodies characteristic of retrogradely transported HRP were defined as double labeled, i.e. cholinergic neurons that project to the amygdaloid body.     

Blood supply of the bed nucleus of the stria terminalis in rat

Summary The topographical distribution of the blood vessels in the bed nucleus of the stria terminalis (NIST) has been mapped in rats. Arteries and veins were visualized in red and blue by using a double-ink perfusion technique. Arteries supplying the NIST arise from the anterior cerebral artery directly or through the anterior communicating and interhemispheric arteries. Only a few, dorsal branches derive from the medial cerebral artery through thalamostriatal arteries. According to their terminal branches, NIST arteries can be divided into five groups: medial, ventral, lateral, septal and dorsal, which have only a relatively small overlap in their territories. About 90% of veins from the NIST drain into the major basal veins. Medial branches run into the perioptic and interhemispheric veins, while the ventral branches and the large lateral vein drain directly into the anterior cerebral vein. A small proportion of NIST veins run dorsalward into the vena cerebri magna via thalamostriatal veins.     

Effect of dexamethasone and hydrocortisone on the course of superovulation in cattle

The effect of hydrocortisone and dexamethasone on superovulation was examined in 12 cows. On the day PMSG was given, each animal received either the first of five daily doses of 250 mg succinate hydrocortisone or one injection of 30 mg dexamethasone. In the 48-hr interval between the injection of PMSG and PGF(2)alpha, the concentration of progesterone rose from 6.97 to 10.22 ng/ml in the experimental groups and only to about 2.8 ng/ml in the control group. In the following days progesterone increased even more, from 15.7 to 26.0 ng/ml seven days after estrus in the experimental group and to 19.25 ng/ml in the control group. The group which received dexamethasone had an average of 4.7 corpora lutea and one embryo flushed per animal. The hydrocortisone group had an average of 2.5 corpora lutea and one cow had two embryos. The control group had 6.2 corpora lutea and 5.2 embryos per animal.     

Loading and translocation of assimilate in the fine veins of sunflower leaves

Abstract The time course of loading and transport of assimilate in sunflower leaves was examined by pulse labelling with ¹⁴CO₂, followed by freeze drying or freeze substitution, and dry autoradiography at both low and high resolution. The five classes of veins, V1-V5 (V5 being smallest), show a division of function: V5 and V4 are engaged in loading and short distance transport; V3 to V1, in long distance translocation. The first high concentration of ¹⁴C is found in two or three phloem parenchyma cells (intermediary cells) of V5 and V4 veins. The sieve elements of V5 and V4 veins do not show comparable concentrations of ¹⁴C at any time. Recently assimilated ¹⁴C is transported by the intermediary cells for distances of about 0.5 mm to the V3 veins. In V3 to V1 veins translocation is in the sieve tubes. Transport in V5 and V4 veins is in two directions, that in V3 to V1, in one direction towards the petiole. The high concentration of ¹⁴C formed in the intermediary cells does not increase further as the assimilate moves to the sieve tubes of the V3 veins, and so is probably the origin of the gradient that drives translocation.     

Relation of coenzyme F420 to the activity of methanogenic microorganisms

Summary The relationship between the coenzyme F₄₂₀ content and the activity of methanogenic microorganisms was investigated under different cultivation conditions in anaerobic reactors. The coenzyme F₄₂₀ concentration depends on the substrate used and the cultivation conditions. Coenzyme F₄₂₀ appears not to be a measure of the total methanogenic activity but rather a measure of the amount of methanogenic microorganisms in mixed anaerobic cultures.     

The value of urine osmolality as an index of stress in the ovine fetus

In ovine fetuses, during 100-130 days of gestation, urine osmolalities less than 175 mosmol/kg water were associated with plasma immunoreactive adrenocorticotrophin (ACTH) concentrations below 40 pg/ml in 40/41 samples. In 18/29 fetuses with urine osmolalities greater than 175 mosmol/kg water plasma ACTH was significantly elevated. In 38 samples of fetal blood there was a significant correlation between plasma ADH and ACTH concentrations. By least squares regression the equation to the line was [ACTH] = 5.06 + 3.70 [ADH] (r = 0.62, P less than 0.001). In 50 samples from fetuses of gestational ages 100-140 days, with urine osmolalities of 302 +/- 86 mosmol/kg (mean +/- SD) the blood pH, pO2 and pCO2 values were not significantly different from those in 50 samples from fetuses with urine osmolalities of 125 +/- 22 mosmol/kg. It is proposed that the measurement of fetal urine osmolality provides a good index of fetal stress. A fetus with a urine osmolality less than 175 mosmol/kg is almost invariably in the optimum, unstressed condition.