A Method for Studying Photosynthetic Capacities of Unicellular Algae Based on in vivo Chlorophyll Fluorescence

The correlation between photosynthesis and DCMU-induced fluorescence increase has been studied in four species of unicellular green algae from inoculation of the cultures to the stationary growth phase. The fluorescence increase induced by DCMU was high in exponentially growing cultures but decreased when the cultures approached the stationary phase of growth. Because of the good correlation between photosynthesis and DCMU-induced fluorescence increase, the fluorescence technique is a promising method for describing changes in photosynthetic capacities of algal populations in natural waters.     

Prostaglandin F<Subscript>2α</Subscript> identified as a Luteolytic Hormone in Sheep

Prostaglandin F_2α is released from the uterus of the sheep in a cyclic fashion, acts primarily in a local manner on the ovary via a counter-current mechanism and is responsible for the periodic regression of the corpus luteum in this species.     

Degradation of Chitotetraose to Chitobiose in the Axenic Rape Rhizosphere

In the presence of intact roots of 2-week-old axenic rape seedlings,added N, N', N', N'-tetraacetylchitotetraose was degradedto N, N'-diacetylchitobiose during 48 h of incubation. Onlyminute amounts of monomer (N-acetyglucosamine) were formed fromadded chitotetraose or chitobiose. The addition of a purifiedchitin suspension caused no measurable formation of degradationproducts. The formation of chitobiose from added chitotetraose was linear,suggesting the action of a constitutive enzyme during the incubationperiod. Key words: Brassica napus (L.) cv. Brink, rhizosphere, N, N'-diacetylchitobiose, N,N',N',N', tetraacetylchitotetraose     

ON THE GUSTATORY EFFECTS OF GYMNEMIC ACID AND MIRACULIN IN DOG, PIG AND RABBIT

The effects of gymnemic acid, 1 mg/ml, and miraculin, 1 mg/mlor in a tablet (Miralin^TM) on the taste response to sucrose,citric acid, NaCl and quinine have been studied in dog, pigand rabbit. In the dog gymnemic acid suppressed the responseto sucrose for about 5 min in two out of three animals. It alsoaffected the response to NaCl. Miraculin caused a slight short-lastingincrease in the response to acid. No effects of the taste modifierswere observed in the pig. In the rabbit gymnemic acid did notsuppress the response to sucrose while miraculin enhanced theresponse to citric acid in one out of three animals for a fewminutes.     

ON THE GUSTATORY EFFECTS OF MONELLIN AND THAUMATIN IN DOG, HAMSTER, PIG AND RABBIT

The electrical activity in the chorda tympani proper nerve ofdog, hamster, pig and rabbit was recorded during stimulationof the tongue with the sweet proteins, monellin and thaumatin,and stimuli representing the four taste qualities. It was observedthat these proteins, which to man taste extremely sweet andin the monkey elicit a significant neural response, caused,except for monellin in the dog, no significant change in theneural activity. On the basis of these results it is suggestedthat different types of ‘sweet’ receptor sites existin mammals.     

A new subspecies of the subalpine meadow viper, Vipera ursinii (Bonaparte) (Reptilia, Viperidae), from Greece

An isolated group of populations of the subalpine meadow viper, Vipera ursinii , from the southern Pindos mountains in Greece is described as a new subspecies. They differ from all other ursinii populations in a number of morphological characters, such as: shorter tail with a low number of subcaudals (lowest for the species); nasal normally divided into two plates or united with nasorostralia; low number of supralabials (6); first three supralabials very large while following ones are much reduced (less than half the height of anterior ones); third supralabial below orbit; lateral blotches and spots on body absent or weakly visible (mainly in some males and juveniles); no dark spots on cheek, labials and lateral and dorsal sides of head (except occipital and postorbital stripes); dorsal zig-zag band markedly jagged or only consisting of a narrow vertebral line.