Glucose phosphate isomerase polymorphism in field populations of the potato cyst nematodes, Globodera rostochiensis and G. pallida

The isozymic variation of glucose phosphate isomerase (GPI) was compared in 20 field populations of potato cyst-nematode (PCN) and related to variation in reference pathotypes of PCN. Populations pathotyped as G. rostochiensis Ro 1 by conventional differential cultivar tests were found to be different from populations of G. pallida. Variation within populations pathoptyped as G. pallida was seen and three populations were found to be similar to the reference G. pallida Pal pathotype. This seemed to be confirmed for two populations using cysts formed on a cultivar resistant to the Pa 1 pathotype when an isoenzyme pattern characteristic of G. palida Pa2 and Pa3 was found. The feasibility of the use of isozyme identification of PCN pathotypes is discussed in the light of these results.     

Reproductive variation and adult size in two co-occurring grasshopper species

ABSTRACT. 1. Egg sizes and clutch sizes of the grasshoppers Chorthippus brunneus (Thunb.) and Myrmeleotettix maculatus (Thunb.) were compared among three years and among three sites less than 1.3 km apart. Relationships between these reproductive traits and date of egg laying, body size and body condition were sought.
2. M.maculatus , the smaller species, laid fewer but larger eggs; and only the eggs of this species showed significant differences between sites and years.
3. A negative correlation between egg size and number per clutch was evident between species and years, but generally not among sites and among individuals of a population.
4. However, a hidden negative correlation between egg size and number was uncovered within populations when the relationship was examined for females of a given mature weight.
5. Variation in the number of eggs per clutch was explained statistically by a positive relationship between female body weight and egg number. Also, both interpopulation and intrapopulation comparisons revealed that for M.maculatus , but not for C.brunneus , females with long hind femurs laid large eggs.     

Effects of rho-fluorophenylalanine on the growth of Lactobacillus arabinosus

p-Fluorophenylalanine has been found to be inhibitory to Lactobacillus arabinosus 17-5. This inhibition has been shown to be competitive with phenylalanine but not with tyrosine, and is described by a low antibacterial index, which varies over a range of approximately 1–20, dependent upon the temporal stage of the culture for which the data are employed in calculation.The organism has been found also to adapt readily to the inhibitor. Evidence that this adjustment involves a mutation to a type with a selective advantage in media containing the inhibitor is presented.Under limiting conditions, which have been described, the organism is capable of greater growth in the presence of both metabolite and antimetabolite than in the presence of the same amount of metabolite alone.Discussion of the significance of the results has been presented.     

Cytotaxonomic observations in tropical Vaccinieae (Ericaceae)

Chromosome numbers are reported for 36 accessions representing 31 species from nine genera of the tribe Vaccinieae, family Ericaceae. The plants are tropical and come from Southeast Asia and Central and South America. The taxonomy of the tribe is outlined in these regions. Genera are often poorly defined and taxa were chosen to reflect the range of variation of the Vaccinieae. Most Southeast Asian Vaccinium species were diploid (2 n = 24) as were those of Agapetes subgenus Agapetes (apart from the Himalayan A. flava ), Agapetes scortechinii and Costera endertii. All other accessions were found to be polyploid. The correlation between polyploidy, geographical distribution and the possession of an 'anatomical complex' of the leaf and stem in Vaccinieae of New Guinea and the neotropics is discussed.     

Changes in the adenine nucleotide content of cysts of Globodera rostochiensis associated with the hatching of juveniles

The content of AMP, ADP and ATP within single cysts of Globodera rostochiensis (60–80 fig dry weight) was determined as ATP to an accuracy of ± 10^-11 mol by a bioluminescent technique, after microenzymic methods had been used to phosphorylate AMP and ADP to ATP. Results for a total of 120 cysts showed that a change occurs in the adenylate energy charge of their contents after they have been exposed to potato root diffusate. Cysts in water had a mean adenylate energy charge of 0–63 (s.E. ± 0–04), but a randomly selected group of cysts after 24 h treatment with potato root diffusate had a significantly lower mean of 0–49±0–04. In a second, similar experiment, cysts in diffusate for only 8 h had an energy charge of 0*55 ± 0–03, but this value was not significantly less than the corresponding mean of o-6i ±0–03 of cysts that remained in water. The results indicate an effect on the metabolism of the unhatched juveniles that occurs too soon after the addition of diffusate to be directly due to any increase in locomotor activity. Apparently, the primary action of the hatching factor had affected many juveniles within 24 h of the addition of potato root diffusate to the cyst.