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Synaptic ribbons during postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus).

Synaptic ribbons, functionally enigmatic structures of mammalian pinealocytes, were studied during the postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus). On day 4 post partum, synaptic ribbons appear in cells that have already started to differentiate into pinealocytes. Between days 4 and 9, an increase in the number of synaptic ribbons occurs, concomitant with the continuing differentiation of the pineal tissue. Between days 9 and 16, when differentiation of this tissue is almost completed, the number of synaptic ribbons decreases and approaches that characteristic of the adult pineal gland. During development, the synaptic ribbons increase in length, and dense core vesicles are frequently found in the vicinity of these structures. It is assumed that a functional relationship exists between dense core vesicles and the synaptic ribbons, which are considered to be engaged in a certain form of secretory activity of the mammalian pineal gland.

Animals

Changes in brain ganglioside composition of normothermic and hibernating golden hamsters (Mesocricetus auratus).

1. Brain ganglioside patterns of normothermic and hibernating golden hamsters (Mesocricetus auratus) and laboratory mice had been investigated. 2. The ganglioside pattern of normothermic golden hamsters in comparison to that of mice is characterized by an unusual high amount of the polar trisialoganglioside GT1. 3. In the hibernating golden hamster in contrast to normothermic counterparts the brain gangliosides are more polar (polysialization-effect). 4. The results are discussed with regard to the hypothesis that neuronal membranes provided with more polar gangliosides at lower environmental temperatures might be more efficient with respect to the high complexation ability of gangliosides with Ca2+-ions.

Animals

A comparative study of the absorption of calcium and the availability of phytate-phosphorus in the golden hamster (Mesocricetus auratus) and the laboratory rat.

1. Balance studies were carried out with rats and golden hamsters (Mesocricetus auratus) given diets high and low in calcium (10.8 and 5.1-5.2 g Ca/kg respectively) and high and low in phytate (3.4 and 1.6 g phytate-phosphorus/kg respectively) in a 2 X 2 factorial experiment. 2. Values for Ca absorption and phytate availability (relative to the amount ingested) and for urinary excretion of Ca and P were significantly higher in the hamster than in the rat for all four diets. 3. Phytate availability was significantly greater on the low-Ca than on the high-Ca diets with both species. 4. Ca absorption was greater on the low-phytate than on the high-phytate diets but the differences were significant only for the hamster. 5. Absorption of both Ca and P was poorly controlled in the hamster compared to the rat.

Animals

Studies on sex chromosomes of four hamster species: Cricetus cricetus, Cricetulus griseus, Mesocricetus auratus, and Phodopus sungorus.

In this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. The mitotic X chromosomes show a striking similarity in G-banding pattern but rather great differences in their C-banding patterns. A presumably homologous euchromatic segment that exhibits two distinct G-bands appears in the X chromosome of each species. The Y chromosome of Cricetus cricetus is in contrast to those of the other species, because it reveals a relatively well-differentiated G- and C-banding pattern. In meiotic metaphase I, interstitial chiasmata can be found in the sex bivalents of Cricetus cricetus and Cricetulus griseus, whereas the gonosomes of Mesocricetus auratus and Phodopus sungorus sungorus are terminally associated. The regions that are involved in pairing or association are always heterochromatic.

Animals

[Classical conditioning of agonistic behavior in the Syrian golden hamster (Mesocricetus auratus Waterhouse)].

Nine different reactions of unconditioned agonistic behavior of golden hamsters (Mesocricetus auratus Waterhouse) which could be elicited by an air blow (UCS) were classically conditioned at a sound of a xylophone (tone g), a previously neutral stimulus. Tone g (CS) was paired with UCS for a different number of trials/day. In all animals exposed to over 20 pairings/day components of the agonistic behavior were brought under the control of CS, but it was not possible to predict which one of the agonistic reactions would appear. Most of the animals generalized and also showed conditioned reactions (CR) when presenting tone c' instead of tone g. When utilizing a differential conditioning procedure the animals learned to discriminate between the different tones. Extinction of CR at tone g was reached after an individually different number of trials.

Acoustic Stimulation

Argyrophilic carcinoids in two Syrian hamsters (Mesocricetus auratus).

Argyrophilic carcinoids were found in 2 Syrian hamsters (Mesocricetus auratus). A solitary neoplasm was located in the glandular stomach of a 25.5-month-old animal that had ingested for 12 months laboratory chow to which arecoline and calcium hydroxide [Ca(OH)2] had been added. In the other hamster, a primary carcinoid of the pancreas had metastasized to the mesenteric lymph nodes and liver; this was in a 22-month-old animal that had ingested for 16 months chow containing added snuff and Ca(OH)I. It is not known whether the carcinoids were spontaneous or induced by the treatment. Argyrophilic carcinoids have previously been reported in only one other rodent species.

Animals

Electron microscopy of cerebral malaria in golden hamsters (Mesocricetus auratus) infected with Plasmodium berghei.

Transmission and scanning electron microscopy of hamster cerebral malaria show that haemorrhages occur following vessel necrosis in animals with low parasitaemias. There is no concurrent thrombosis nor packing of capillaries with parasitised erythrocytes. Small vessels contain numerous monocytes which have phagocytosed erythrocytes and smaller particles of similar electron density. The monocytes attach to and migrate through the endothelium but then remain in close proximity to the vessels. Irregular dense deposits are present in the basement membrane of some animals 14 days after infection. These may be immune complexes. The pathogenesis of cerebral malaria is discussed in relation to these findings.

Animals

[A serological study concerning the role of the golden hamster (Mesocricetus auratus) in transmitting lymphocytic choriomeningitis virus to humans (author's transl)].

A search for lymphocytic choriomeningitis (LCM) virus-specific antibody was conducted in 580 persons. One group consisted of 190 14-year-old to 17-year-old girls. In 149 of these hamster contact, either recently or in the more distant past, was certain; three had antibody. In 41 girls hamster contact was doubtful and one was positive. In a second group consisting of 390 persons of either sex and all ages the question as to association with hamsters was answered 123 times in the affirmative. Hamster contact was denied 251 times and uncertain 16 times. In sera from five individuals of this group antibody to LCM virus was detected; they all confirmed having had contact with hamsters.

Adolescent

The causation of two scent-marking behaviour patterns in female hamsters (Mesocricetus auratus).

Social, olfactory, and oestrous cycle influences on the frequency of flank-marking and vaginal marking were studied in female hamsters. Vaginal marking was more frequent in the presence of males or their odours than females or their odours. Vaginal marking frequency was greatest the day before oestrus (day 4), intermediate on days 2 and 3, and zero on the oestrous day. The probable sexual advertisement functions of vaginal marking were discussed. In contrast, flank-marking by females was stimulated more by other female odours than by male odours. The frequency of flank-marking was elevated by agonistic encounters and was reduced by sexual encounters. Flank-marking seems to have functions related to functions of aggression among hamsters.

Aggression

Hemolytic assay of complement and its components from Syrian hamster (Mesocricetus auratus) and Mongolian gerbil (Mariones unguiculatus).

Syrian hamster sera may be assayed for hemolytic complement (C) activity by standard procedures with sensitized sheep erythrocytes as used for human sera, but mongolian gerbil sera had higher complement titers when tested with sensitized guinea pig erythrocytes as target cells. The optimal conditions for in vitro testing of hamster C were pH 7.3, ionic strength 0.15, and presence of 1 micrometer of Mg2+ and 0.3 micrometer Ca2+. For gerbil C the optimum pH was 8, ionic strength 0.074, and the same concentration of Mg2+ and Ca2+ as for hamster. Incubation at 37 degrees C for 60 minutes yielded optimal results. Complement components in the serum of both species could be tested with commercially prepared intermediates of sheep erythrocytes pretreated with guinea pig C1 and human C4 respectively, using purified human C2 through 9 and standard methods applied for testing human C components. Both species have all nine components of the complement system.

Animals