Spotting genes and internal pigmentation patterns in the mouse

Development ◽  
1971 ◽  
Vol 26 (1) ◽  
pp. 123-133
Author(s):  
M. S. Deol
Keyword(s):  
Inner Ear ◽  
Strong Support ◽  
Harderian Gland ◽  
Host Tissue ◽  
Host Tissues

Hereditary white spotting in the mouse may be caused by genes at over a dozen loci. It is thought that some genes achieve their effects by acting through the melanoblasts, and others by acting through the host tissue. The genes mi, Miwh, Wv and s are believed to belong to the former category. But it is not known how the abnormality of the melanoblasts is transformed into the spotting patterns observed. According to one view, the capacity of the melanoblasts to respond to some melanogenesis-promoting factor in the host tissues is impaired, and as all melanoblasts are affected about equally, the pattern depends on normal variations in the distribution of this factor in the host tissue. According to another, a proportion of the melanoblasts are ‘preprogrammed’ to die before differentiation. Both views are largely based on studies on the coat. It was thought that an investigation of the spotting patterns in the choroid, the Harderian gland and the inner ear might throw fresh light on the problem. This was carried out in the genotypes +/mi, Miwh/+, Wv/+, Wv/Wv and s/s. The results provide strong support for the view that all melanoblasts are affected and the host tissue plays an important role in determining the pattern of spotting. However, there appear to be some indications that all melanoblasts may not be affected to the same degree.

Morphogenetic properties of the skin axolotl limb regeneration

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 265-288
Author(s):  
Jonathan M. W. Slack
Keyword(s):  
Limb Regeneration ◽  
Host Tissue ◽  
Tissue Formation ◽  
Cellular Composition ◽  
Posterior Half ◽  
Tail Bud ◽  
Threshold Theory ◽  
Anterior Side ◽  
Immunological Rejection ◽  
Host Tissues

A study has been made of the morphogenetic properties of anterior and posterior skin from the lower forelimb of the axolotl. The basic experiment consisted of a graft of a half cuff of skin from a donor to a host limb followed by a 2-week healing period, amputation through the graft, and a study of the resulting regenerate. Limbs with double posterior skin formed double posterior regenerates and, in contrast, limbs with double anterior skin formed normal or slightly hypomorphic regenerates. Posterior skin from post-metamorphic animals had a similar but weaker effect to that from ordinary axolotls. Immunological rejection of allografts could be completely avoided if the donor limb was transplanted to the flank of the host when both were at the stage of tail-bud embryos, and the skin graft was later carried out between the supernumerary limb and one of the host limbs. This technique was used to show that immunological rejection does not affect the formation of duplicates from the limbs with double posterior skin, and to facilitate the studies of the cellular provenance of the regenerate. The cellular composition of duplicate regenerates was studied by using both triploid donors and triploid hosts. It was shown that the posterior side of the duplications consisted wholly of host tissue and the anterior side consisted of mixed donor and host tissue. Formation of the duplicated regenerate therefore seems to involve positional reprogramming of both donor and host tissues together with metaplasia of the donor tissue. It was not possible to inhibit the duplication-inducing property of posterior skin by treatment with a variety of enzymes. A model based on the serial threshold theory of regeneration is advanced to explain the results.This model successfully accounts for the observed non-equivalence of anterior and posterior skin, and also explains the different regeneration behaviour of anterior and posterior half limbs, the limited regeneration of double anterior limbs, and the pattern expansion and contraction shown by regenerates from double posterior limbs.

RIBONUCLEASE ACTIVITY IN RUSTED WHEAT LEAVES

1961 ◽  
Vol 39 (4) ◽  
pp. 775-784 ◽  
Author(s):  
R. Rohringer ◽  
D. J. Samborski ◽  
C. O. Person
Keyword(s):  
Leaf Rust ◽  
Direct Evidence ◽  
Specific Activity ◽  
Host Tissue ◽  
Ribonuclease Activity ◽  
Rnase Activity ◽  
Rnase Inhibitor ◽  
Germination Medium ◽  
Wheat Leaves ◽  
Host Tissues

Extracts from primary leaves of Lee wheat were prepared at various days following inoculation with races of leaf rust and tested for ribonuclease (RNase) activity. As early as 24 hours after inoculation there was a marked increase in the specific activity of the enzyme in extracts of rusted host tissues. A further increase in activity was observed during later stages of infection, with the susceptible and resistant reacting tissue differing only in the degree of their response. Extracts from noninoculated control leaves exhibited a constant RNase activity throughout the period of observation. The germination medium and extracts from germinating uredospores contained comparatively little RNase activity. No direct evidence was obtained either for the possible release of the enzyme from particulate cellular fractions of the host tissue as a result of infection or for the removal of an RNase inhibitor in the host tissue responding to infection.

Mast cell response during the early phase of tuberculosis: an electron-microscopic study

1977 ◽  
Vol 23 (9) ◽  
pp. 1245-1251 ◽  
Author(s):  
Samuel Ratnam ◽  
Shobhitha Ratnam ◽  
B. K. Puri ◽  
Saroj Chandrasekhar
Keyword(s):  
Mast Cell ◽  
Mycobacterium Tuberculosis ◽  
Electron Microscope ◽  
Host Tissue ◽  
Tuberculous Infection ◽  
Electron Microscopic ◽  
Morphological Alterations ◽  
Dense Bodies ◽  
Large Numbers ◽  
Host Tissues

Guinea pig lungs were infected with Mycobacterium tuberculosis by intratracheal route and examined under electron microscope to investigate the morphological alterations of the organisms, if any, and the response of the host tissue. The bacilli showed no changes in their morphology, while the host tissues revealed several cells containing many electron-dense intracytoplasmic granules. These cells were predominantly seen during the 1st week of infection. The electron-dense bodies of these cells may be the ones observed by earlier workers and suggested to be the altered forms of tubercle bacilli. The present investigation, however, revealed them to be the granules of the mast cells. These cells were observed to respond to tuberculous infection during the first few days by appearing in large numbers crowded with intracytoplasmic granules and soon disintegrating as the result of subsequent degranulation. The above observation is presented and its significance discussed.

Ectopic induction and reorganization of Wnt-1 expression in quail/chick chimeras

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3379-3394 ◽  
Author(s):  
L. Bally-Cuif ◽  
M. Wassef
Keyword(s):  
Expression Profile ◽  
Host Tissue ◽  
Host Embryo ◽  
Positive Line ◽  
Host Tissues

When grafted ectopically into the diencephalon of a chick host embryo, a portion of met-mesencephalon straddling the met-mesencephalic constriction has the capacity to induce En-2 expression in the surrounding host tissue. Subsequently, tectal and cerebellar structures, composed of both host and grafted cells, are reconstructed in this ectopic location at the expense of the host diencephalon. Previous experiments indicated that the induction of En-2 was correlated with Wnt-1 expression within the graft. The aim of the present study was: (i) to determine whether Wnt-1 expression was spatially regulated within the graft, (ii) to investigate whether host Wnt-1-expressing cells were also involved in the ectopic met-mesencephalic development and, if so, (iii) to localize these Wnt-1-positive domains in relation to the patterning of the ectopically developing met-mesencephalic territory. We studied the expression profile of Wnt-1, in relation with that of other positional markers, in quail/chick chimeras where various portions of met-mesencephalon had been grafted into the diencephalon. We found that Wnt-1 expression was reorganized within the graft, and that it was also induced in the host in contact with the graft. Moreover, these ectopic expressions of Wnt-1, in both the grafted and the surrounding host tissues, were organized in concert to form a continuous positive line at the host/graft junction, the location of which depended on the precise origin of the graft. Finally, we found that this line was frequently located at the limit between territories expressing different positional markers. We propose that Wnt-1 expression is turned on at the junction between domains of different phenotypes, and may be used as a border to stabilize these adjacent differently committed territories.

scholarly journals Insight into motility-dependent pathogenicity of the zoonotic spirochete Leptospira

2020 ◽  
Author(s):  
Jun Xu ◽  
Nobuo Koizumi ◽  
Shuichi Nakamura
Keyword(s):  
Host Tissue ◽  
Solid Surfaces ◽  
Host Cells ◽  
Bacterial Motility ◽  
Kidney Cells ◽  
Pathogenic Species ◽  
Tissue Surfaces ◽  
Crawling Motility ◽  
Insight Into ◽  
Host Tissues

AbstractBacterial motility is crucial for many pathogenic species in the process of invasion and/or dissemination. The spirochete bacteria Leptospira spp. cause symptoms, such as hemorrhage, jaundice, and nephritis, in diverse mammals including humans. Although loss-of-motility attenuate the spirochete, the mechanism of the motility-dependent pathogenicity is unknown. Here, focusing on that Leptospira spp. swim in liquid and crawl on solid surfaces, we investigated the spirochetal dynamics on the host tissues by infecting cultured kidney cells from various species with pathogenic and nonpathogenic leptospires. We found that, in the case of the pathogenic leptospires, a larger fraction of bacteria attached to the host cells and persistently traveled long distances using the crawling mechanism. Our results associate the kinetics and kinematic features of the spirochetal pathogens with their virulence.One Sentence SummaryAdhesivity and crawling motility over host tissue surfaces are closely related to the pathogenicity of a zoonotic spirochete.

The structure and development of the haustorium in Cuscuta australis

1989 ◽  
Vol 67 (10) ◽  
pp. 2975-2982 ◽  
Author(s):  
Kyu Bae Lee ◽  
Chai Doo Lee
Keyword(s):  
Light And Electron Microscopy ◽  
Cell Types ◽  
Host Tissue ◽  
Cortical Cells ◽  
Meristematic Cells ◽  
Dense Cytoplasm ◽  
Trifolium Repens L ◽  
Tip Cells ◽  
Region Ii ◽  
Host Tissues

The structure and development of the haustorium of a parasitic angiosperm Cuscuta australis R. Brown growing on the host plant Trifolium repens L. was studied with light and electron microscopy. The upper haustorium, which lies external to the host organ, initiates endogenously from cortical cells of the middle layers of the parasite stem. The initial cells develop into a group of meristematic cells. As haustorial maturation progresses, the meristematic cells develop into an endophyte primordium that penetrates the host tissue. The endophyte primordium consists of three cell types: (i) remarkably enlarged elongate cells (digitate cells) with very dense cytoplasm and large nuclei at the central region; (ii) smaller file cells with prominent nuclei proximal to the digitate cells; and (iii) highly compressed cells distal to the digitate cells. Evidence suggests that the digitate cells are metabolically very active. The endophyte, which lies internal to the host tissue, consists of parenchymatous axial cells and elongate tip cells with dense cytoplasm and conspicuous nuclei. The axial and tip cells of endophyte are interpreted as originating from the file and digitate cells of the endophyte primordium, respectively. The tip cells independently penetrate the host tissues and transform into the filamentous hyphae. The hyphae reach the host vascular tissues and eventually differentiate into xylary or phloic conductive hyphae.

Evasion of the haemocytic defence reaction of certain insects by larvae of Hymenolepis diminuta (Cestoda)

Parasitology ◽  
1976 ◽  
Vol 73 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Ann M. Lackie
Keyword(s):  
Schistocerca Gregaria ◽  
Host Tissue ◽  
Hymenolepis Diminuta ◽  
Insect Species ◽  
Defence Reaction ◽  
Latex Beads ◽  
Host Tissues

SummaryLarvae of Hymenolepis diminuta develop in the haemocoele of the beetles Tribolium and Tenebrio, and of the locust Schistocerca gregaria, without being encapsulated by haemocytes. The mechanism of this evasion of the haemocytic defence reaction has been examined using various techniques. Larvae grown in culture and injected into S. gregaria have few or no haemocytes adherent even after 8 h, although latex beads injected at the same time have been thickly encapsulated. This, and results of transplanting cysticercoids and host tissue between different insect species, suggests that the surface of the larvae may bear an inherent similarity to the surface of host tissues and thus escape recognition as ‘not-self’ by the host’s haemocytes.

scholarly journals Pathology induced by Pomporhynchus kashmiriensis (Acanthocephala) in the alimentary canal of naturally infected Chirruh snow trout, Schizothorax esocinus (Heckel)

2012 ◽  
Vol 49 (1) ◽  
pp. 11-15 ◽  
Author(s):  
M. Irshadullah ◽  
Y. Mustafa
Keyword(s):  
Light Microscopy ◽  
Alimentary Canal ◽  
External Surface ◽  
Host Tissue ◽  
Cell Mediated Immunity ◽  
Snow Trout ◽  
Host Parasite ◽  
Acanthocephalan Parasite ◽  
Macroscopic Examination ◽  
Host Tissues

AbstractHistopathology of the alimentary canal of Chirruh snowtrout, Scizothorax esocinus (Heckel), naturally infected with the acanthocephalan parasite, Pomphorhynchus kashmiriensis was studied by light microscopy. The proboscis and bulb was found to be deeply penetrated into the host tissues. Macroscopic examination revealed over secretion of mucous and shedding of host tissues at the host parasite interface and white fibrous nodules on the external surface of infected intestine, which was an indication for the presence of parasite. The major changes in parasite induced histopathology were at the site of attachment to the host’s intestine which includes destruction of villi and epithelial linings. Increased cellular infiltrations at the site of attachment may be a consequence of host’s defence involving cell mediated immunity. In the areas of trunk contact with the host tissue, compression/absence of intestinal folds and loss of columnar appearance of epithelial cells were evident.

The infection process of Puccinia xanthii f. sp. ambrosiae-trifidae on Ambrosia trifida

Botany ◽  
2011 ◽  
Vol 89 (11) ◽  
pp. 771-777 ◽  
Author(s):  
Ping Zhang ◽  
Guo-zhong Lu ◽  
Xiao-dong Sun ◽  
Wei Zhang ◽  
Bo Qu ◽  
...  
Keyword(s):  
Leaf Surface ◽  
Rust Fungus ◽  
Infection Process ◽  
Host Tissue ◽  
Liaoning Province ◽  
Invasive Weed ◽  
Ambrosia Trifida ◽  
Teliospore Germination ◽  
Germ Tubes ◽  
Host Tissues

Puccinia xanthii Schwein. f. sp. ambrosiae-trifidae S.W.T. Batra is an obligate parasitic rust fungus of Ambrosia trifida Linn. Field investigations in Liaoning Province, China, showed that it is an effective biocontrol agent of this alien invasive weed. Its infection of the plant was observed by light microscopy combined with Coomassie Brilliant Blue R-250 staining. We report the infection process, including teliospore germination and basidiospore formation on the host leaf surface, penetration of host tissue, and development of fungal hyphae within the host tissue. Fresh teliospores began to germinate from the germ pore within 1 h under suitable conditions and soon produced basidiospores or secondary basidiospores. Basidiospores falling on host leaves germinated from the end of the basidiospore opposite to the apiculus. Appressoria of germ tubes tended to orient along leaf epidermis cell ridges or at junctions near stomata rather than fixing randomly on the leaf surface. These germ tubes grew for short or longer distances before forming appressoria. The rust fungus directly penetrated the host epidermis by infectious pegs rather than through stomata. Within host tissues, the rust fungus formed intraepidermal vesicles, primary hyphae, intracellular hyphae, and M-haustoria. The intricate infectious structures formed by P. xanthii f. sp. ambrosiae-trifidae on or in host tissues suggest that the rust fungus is a suitable organism for researching the interaction between the pathogen and host plant.

Implantation of adult Onchocerca gutturosa into laboratory rodents

Parasitology ◽  
1987 ◽  
Vol 95 (1) ◽  
pp. 155-158 ◽  
Author(s):  
K. A. El Sinnary ◽  
A. E. Bianco ◽  
J. F. Williams
Keyword(s):  
Connective Tissue ◽  
Peritoneal Cavity ◽  
Host Tissue ◽  
Post Mortem ◽  
Adult Males ◽  
Post Mortem Examination ◽  
Laboratory Rodents ◽  
Males And Females ◽  
Host Tissues

SUMMARYAdult males and females ofOnchocerca gutturosawere implanted into the peritoneal cavity of mice, and their survival was determined at intervals thereafter by post-mortem examination. Ten of 17 animals receiving males dissected free of bovine host tissues contained live parasites at necropsy up to 4 months later. Female worms digested free from connective tissue by collagenase did not survive well, even though they appeared motile and intact before implantation; only 2 were alive 10 days later in 2 of 16 recipients. When males and females still contained within connective tissue capsules were implanted they survived for up to 2 months, and microfilariae were detected transiently in the skin of 2 recipient mice. The results suggest the feasibility of maintaining adultO. gutturosain rodents by this means, provided exposure of worms to enzymes used to free them from host tissue is avoided.

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