Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni

Knopf P. M. and Soliman M. 1980. Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni. International Journal for Parasitology, 10: 197–204. The capacity of Schistosoma mansoni to complete its life cycle was compared in CD-1 mice (permissive hosts) and Sprague-Dawley rats (nonpermissive hosts) from which the pituitary gland had been removed prior to infection with cercariae. Except for a modest decrease in egg burden, none of the parameters of worm life cycle assessed were affected in hypophysectomized mice. In contrast, all these parameters were affected in hypophysectomized rats, e.g. onset of adult worm elimination was delayed, worm development improved, oviposition increased and miracidia developed. Effects of removal from rats of the thyroid/parathyroid glands on the parasite life cycle were similar to hypophysectomy; adrenalectomy or gonadectomy were without affect. Differences between thyroidectomized and thymectomized rats are discussed. It is concluded that host hormones contribute to the nonpermissive status of rats to Schistosoma mansoni infections.     

Intestinal endocrine cells of chicks around the time of hatching

Summary The duodenum of 16-day Black Australorp chick embryos, and the duodenum, ileum, large intestine and caeca of 18-day embryos and of chicks within 30 h of hatching, have been studied by electron microscopy. Cells were found with secretory granules resembling those in mammalian EC, S, A-like, EG and D cells (terminology of Solcia et al., 1973), and were on this basis tentatively identified accordingly. The distribution and frequency of the chick cells in different parts of the tract correspond well to the situation in mammals.Supported by grants from the Senate Research Committee of the University of the Witwatersrand, JohannesburgThe author gratefully acknowledges the help of Professors E. Solcia and N. Ferreira     

Etude ultrastructurale de l'innervation des glandes salivaires postérieures chez Octopus vulgaris

Résumé Le canal salivaire contient dans sa paroi deux types de nerfs, moteurs et sécréteurs. Le diamètre des fibres nerveuses est en moyenne plus faible dans les nerfs moteurs, où il diminue encore en direction des glandes, tandis qu'au contraire celui des fibres sécrétrices augmente, accentuant ainsi les différences morphologiques entre les deux ners. Ces différences de calibre entre les fibres sont en rapport avec le nombre plus ou moins élevé des neurites qu'elles comportent, et dont les mésaxones ont des formes variées. Les caractères cytologiques des cellules satellites et des axones des deux types de nerfs sont comparables. Les axones contiennent des vésicules de types morphologiques très divers dont la signification est discutée.

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Ultrastructural study of the innervation of the posterior salivary glands in Octopus vulgaris I. The nervous trunks of the salivary duct

Summary Two types of nerves, motor and secretory, are found in the wall of the salivary duct. The average diameter of the motor fibers is smaller and decreases still more towards the glands, while on the contrary it increases for the secretory fibers. The disparity of diameter between the two types of fibers is due to the different number of neurites they contain, embedded in satellite cells with mesaxons of various forms. Axons and satellite cells have similar cytological features in the two types of nerves. Vesicles of several morphological types occur in the axons; their significance is discussed.

     

黑缘烟蟋螽丝腺结构

【目的】蟋螽是直翅目中唯一具有吐丝筑巢行为的类群。本研究旨在探讨蟋螽丝腺的结构特点。【方法】应用解剖学观察、免疫荧光、苏木精-伊红染色、PAS苏木精染色、扫描电镜和透射电镜等方法从细胞水平对黑缘烟蟋螽Capnogryllacris nigromarginata丝腺的显微与超微结构进行了观察。【结果】黑缘烟蟋螽丝腺由导管和腺泡构成。腺泡由鞘细胞延伸形成的结缔组织鞘包围。腺泡的主体有4种细胞,分别为Ⅰ型分泌细胞、Ⅱ型分泌细胞、围细胞和腔细胞。Ⅰ型和Ⅱ型分泌细胞为大的腺细胞,形状不规则。分泌细胞细胞核很大,胞质内有大量的内质网和分泌颗粒。Ⅰ型分泌细胞靠近腺泡中心,PAS-苏木精染色表明Ⅰ型分泌细胞内含糖蛋白,Ⅱ型分泌细胞在腺泡外周,位于Ⅰ型分泌细胞与围细胞或结缔组织鞘之间。腔细胞分散在分泌细胞之间,包围形成胞外运输分泌物的通道。围细胞与鞘细胞接触,具有由细胞膜内陷形成的微绒毛腔,胞质内有大量的线粒体。围细胞微绒毛腔与腔细胞包围的细胞外运输通道相连,分泌细胞分泌的颗粒聚集在分泌细胞和胞外运输通道之间的连接处,并将分泌物排出至胞外运输通道。多个腺泡的胞外运输通道汇集到由单层细胞组成的丝腺导管。单层导管细胞靠近管腔外围具有规则排列的质膜内陷和大量伸长的线粒体;靠近管腔的一侧具连续的细胞膜突起,在导管壁的表皮下紧密排列。【结论】黑缘烟蟋螽丝腺分泌细胞分为Ⅰ型分泌细胞和Ⅱ型分泌细胞。分泌物质产生及分泌过程依次经过分泌细胞、腔细胞包围的胞外通道、分支导管、总导管和唾窦。其中在腺泡细胞之间,分泌物向外运输过程中,围细胞微绒毛腔的微丝束可能对分泌物的外排提供推动力。     

甘草叶片形态结构和光合作用对干旱胁迫的响应

叶片结构在植物防御生物和非生物胁迫方面起着重要的作用,可通过合成、储存和分泌次生代谢产物提高植物抗性。以甘草幼苗为试材,采用盆栽控水自然干旱法,探讨叶片光合作用、气孔微形态和腺体形态对干旱胁迫的响应。结果表明:①随着干旱胁迫程度的加剧,叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均呈先升高后降低的趋势;其中胞间CO2浓度(Ci)在重度干旱胁迫(severe stress,SS)时迅速增高。②随着干旱胁迫程度的加剧,叶片总气孔密度和气孔开张比呈先增大后减小的趋势;而气孔开张宽度呈逐渐减小的趋势。③随着干旱胁迫程度的加剧,叶片上表皮和下表皮腺体密度总数整体上呈增大的趋势,腺体颜色随着干旱胁迫程度的加剧逐渐加深,形状出现不规则褶皱和内陷。总之,甘草叶片表面的腺体特征参与抗旱逆境调节,从而避免干旱胁迫对甘草植株的伤害;在SS下,胁迫程度加速了气孔细胞的程序性死亡(PCD),甘草幼苗失去抗旱能力。     

Dislodgement effect of natural semiochemicals released by disturbed triatomines: a possible alternative monitoring tool

The quick detection of domestic and peridomestic triatomines in their environments becomes difficult without the use of dislodgement substances that flush them out from their shelters. At present, tetramethrin 0.2% is being widely used in control programs. Although it is an efficient dislodging agent, its toxicity might affect the health of captured triatomines, of other insects and, to a lesser extent, of other animals, including humans. Here, we tested if semiochemicals released by disturbed adults of Triatoma infestans and/or Rhodnius prolixus can make larvae of the same species exit from their refuges. In a walking olfactometer we found that: 1) larvae of T. infestans were repelled by the odors released by disturbed adults of their own species and of R. prolixus, 2) larvae of R. prolixus did not change their behavior in the presence of odors released by adults of both species, and 3) activity levels were not modulated by these odors in any of both species. Besides, in pseudo‐natural conditions we found an increased flushing‐out activity of larvae of T. infestans when their shelters were sprayed with isobutyric acid or 3‐pentanol, and of larvae of R. prolixus when sprayed with 3‐methyl1butanol. We succeeded in this work to dislodge larvae of triatomines from artificial shelters using natural volatile compounds, allowing the capture of live bugs for further investigations (e.g., xenodiagnosis or genetic studies) and favoring ecological aspects (e.g., minimizing environmental insecticide‐contamination and non‐targeted mortality).     

Sweat rate and sweat composition during heat acclimation

The purpose of this study was to determine local sweat rate (LSR) and sweat composition during heat acclimation (HA). For ten consecutive days of HA, eight participants cycled in 33 °C and 65% relative humidity at an intensity such that a rectal temperature of 38.5 °C was reached within ~40 min, followed by a 60-min clamp of this rectal temperature (i.e., controlled hyperthermia). Four participants extended HA by a 28-day decay period and five consecutive days of heat re-acclimation (HRA) using controlled hyperthermia. Sweat from the upper arm and upper back was collected three times during each heat exposure session. LSR and sweat sodium, chloride, lactate, and potassium concentrations were determined. Relative to HA day 1, LSR was increased at the final day of HA (day 10) (arm: +58%, P < 0.001; back: +36%, P < 0.05). Concentrations of sodium, chloride, and lactate significantly (P < 0.05) decreased to ~60% at HA day 10 compared to day 1 on the arm and back. Potassium concentration did not significantly differ on HA day 10 compared to day 1 (arm: +11%, P > 0.05; back: +8%, P > 0.05). The induction patterns of the sudomotor adaptations were different. Whilst LSR increased from HA day 8 on the arm and from HA day 7 on the back, sodium and chloride conservation already occurred from HA day 3 on both skin sites. Lastly, the sweat lactate reduction occurred from HA day 6 on the arm and back. Initial evidence is provided that adaptations were partly conserved after decay (28 days) and that a 5-day HRA may be sufficient to restore HA adaptations. In conclusion, ten days of exercise-induced HA using controlled hyperthermia led to increases in LSR and concomitant reductions of sweat sodium, chloride, and lactate concentrations, whilst potassium concentrations remained relatively constant.