Summary

A technique has been developed which allows the isolation of random deletions extending from unique restriction enzyme sites in plasmid DNA molecules. The method involves transformation of E. coli cells with linear plasmid DNAs generated by restriction enzyme cleavage. We have used this technique to map DNA transfer genes in the tra control region of F sex factor DNA. Deletions within EcoRI fragment f6 of F DNA have been isolated and used to assign physical locations to tra genes by a combination of genetic complementation tests, restriction enzyme analysis, DNA heteroduplexing and the analysis of the proteins synthesised in minicells and in vitro. Deletion analysis has also allowed the identification of the traK gene product.

This paper describes the identification and quantitative analysis of cytokinins from natural sources (150–500 g fresh weight) at the submicrogram level. It summarizes an improved purification procedure with high resolution power that permits the detection of Trimethylsilylderivatives by gas chromatography-mass spectrometry. A comparison of the intensity of a characteristic ion in the mass spectrum of suitable standard (5 μg) and theintensity of the same ion in the mass spectrum of the extraction product permitted precise quantitative analysis. The method has been used to determine zeatin, trans- and cis-ribosylzeatin, and Δ²-isopentenyladenosine concentrations in extracts from female and monoecious Mercurialis ambigua apices. It has been proved that differences appear in the endogenous cytokinin pools of monoecious and female individuals.

The thiobarbituric acid (TBA) test has been used in the field of medical science in recent years to detect lipid peroxides. In this case, it is necessary for hydroperoxides to be decomposed to secondary products during the reaction. When purified methyl linoleate and methyl linolenate monohydro-peroxides were used as the sample for the TBA test, they did not decompose entirely to secondary products, but did so completely when an iron catalyst (ferrous sulfate) was added. However, the iron catalyst also accelerated the autoxidation of coexisting unsaturated fatty acids. Therefore, the addition of antioxidants was required. Fifteen min of heating was sufficient to complete the reaction. With additions of catalyst and antioxidant to the TBA test, it may be possible to make useful distinctions between hydroperoxides and secondary products of lipid oxidation.

During cadmium uptake by the shore crab Carcinus maenas (L.), cadmium appears in both haemolymph and urine within 1 h, and comes into equilibrium with the haemolymp after some 60 h. The equilibrium concentration for haemolymph cadmium is always considerably less than that of the external medium, whether the latter is close to background level or at the artificially high concentration of 2.2 mg l^-1. Despite earlier evidence that cadmium entering the haemolymph is mainly bound to protein, current results show most of this to be freely labile and quickly displaced by cadmium taken up subsequently. There is some evidence to suggest that cadmium is passed on from the haemolymph to the hepatopancreas. A large proportion of whole-body cadmium is adsorbed onto the exoskeleton and gills. The comparatively rapid efflux of ¹⁰⁹Cd from loaded crabs over a period of 1 week is mainly due to desorption of this cadmium from the outer body surface.

The reef-building coral Montastrea cavernosa Linnaeus possesses sweeper tentacles which have enlarged nematocyst batteries. Sweeper tentacles appear to be used in defense of the coral's living space and may successfully deter mesenterial filament attacks from the more aggressive coral M. annularis. M. cavernosa therefore possesses a specialized defensive strategy that has not been taken into account by present models describing spatial competition in coral reef ecosystems.

Primate nurseries have traditionally collected weight and intake data to construct growth norms for their populations. The purpose of this paper is to suggest supplementing these data with skeletal maturation and linear body growth information. Methods of assessment used at the Infant Primate Research Laboratory at the University of Washington are presented, using as an example a current study which contrasts the physical growth and ossification status of premature and term-gestation pigtail macaques (Macaca nemestrina). The postnatal growth and development of the macaque is of special interest as a model for the human infant. The fetal and infant growth of the macaque is similar to the human skeletal growth and maturation process (Kerr, 1975; Newell-Morris and Tarrant, 1978). Hand and foot ossification is much more rapid than in the human, reducing follow-up time for the appearance of round bones and epiphyses to months instead of years of postnatal age. Previous studies have indicated the value of ossification onset and increments as measures of skeletal maturity (Pryor, 1906; Flory, 1936; Garn and Rohmann, 1959, 1968; van Wagenen and Asling, 1964; Kerr, 1975). Skeletal growth and ossification assess­ment can provide a more detailed picture of infant maturation status than age estimates and weight alone and may have predic­tive value for later growth and development.

Cedar apple rust is an appropriate name for a disease caused by a fungus that attacks both the cedar and the apple. It is also fitting since the reddish galls produced on the cedar are called cedar apples! This disease is caused by Gymnosporangium juniperi-virginianae. Two similar diseases, Hawthorn rust and quince rust, are caused by closely related fungi, Gymnosporangium globosum and Gymnosporangium clavipes, respectively. These three fungi and related species are heteroecious and demicyclic, a form of macrocyclic species in which no uredial stages occur. No uredial stages occur in most species of Gymnosporangium.