Pathways for metabolism of ketoaldonic acids in an Erwinia sp.

The pathways involved in the metabolism of ketoaldonic acids by Erwinia sp. strain ATCC 39140 have been investigated by use of a combination of enzyme assays and isolation of bacterial mutants. The catabolism of 2,5-diketo-D-gluconate (2,5-DKG) to gluconate can proceed by two separate NAD(P)H-dependent pathways. The first pathway involves the direct reduction of 2,5-DKG to 5-keto-D-gluconate, which is then reduced to gluconate. The second pathway involves the consecutive reduction of 2,5-DKG to 2-keto-L-gulonate and L-idonic acid, which is then oxidized to 5-keto-D-gluconate, which is then reduced to gluconate. Gluconate, which can also be produced by the NAD(P)H-dependent reduction of 2-keto-D-gluconate, is phosphorylated to 6-phosphogluconate and further metabolized through the pentose phosphate pathway. No evidence was found for the existence of the Entner-Doudoroff pathway in this strain.     

Role of prostaglandins in the behavioral changes induced by murine interleukin 1 alpha in the rat

Continuous infusion of murine recombinant interleukin 1 alpha (rIL-1 alpha) produces weight loss, appetite suppression, reduction in horizontal locomotor activity (crossovers) and vertical locomotor activity (rears), and an increase in drinking behavior in the rat. The role of prostaglandins (PG) in the elicitation of these effects was studied. Infusion of rIL-1 alpha produced a transient increase in serum (PGs) which peaked at 24 to 48 h. This increase was completely inhibited by piroxicam. However, inhibition of circulating PG by piroxicam did not block the reductions in appetite, crossover, and rears induced by rIL-1 alpha; it restored normal drinking behavior and only partially restored body weight. Continuous intraperitoneal infusion of PGE2 at 24 micrograms/day exposed the animals to serum levels of PGE2 comparable to those produced by infusion with rIL-1 alpha. Yet, at the point of maximum weight loss induced by rIL-1 alpha (72 h), PGE2 infusion resulted in only a quarter of the weight loss. Compared with rIL-1 alpha, continuously infused PGE2 produced significantly smaller reductions in appetite, crossovers, and rears, and had no effect on drinking behavior. From these observations, we conclude that the rIL-1 alpha-induced increase in drinking behavior was fully dependent on products of the cyclooxygenase pathway, but not necessarily PGE2. However, because of the failure of piroxicam to fully reverse rIL-1 alpha effects on eating, mobility, and weight loss, there must also be a significant PG-independent component to account for the full range of rIL-1 alpha effects.     

Leukotriene C4 ([3H] - LTC4) binding to membranes isolated from a hamster smooth muscle cell line (DDTIMF2)

Leukotriene C₄ (LTC₄) has been demonstrated to induce contraction of the smooth muscle cell line DDTIMF2. A partially purified membrane fraction obtained from these cells exhibited a high affinity binding site for LTC₄. Binding of [³H]-LTC₄ was saturable, specific and reversible with a dissociation constant (K_d) of 21 ± 4 nM. The maximum number of binding sites (B_max) was 55 ± 5 pmol/mg of protein. Specificity was demonstrated in competition studies in which the Ki of LTC₄ against specifically bound [³H] - LTC₄ was 12 nM whereas Leukotriene D₄ (LTD₄) and Leukotriene E₄ (LTE₄) had a Ki of 38 ± 4 and 4.7 ± 0.5 nM respectively. A previously described antagonist of leukotriene-induced smooth muscle contraction PFL 55712 had a K_i of 23 ± 2 nM as determined by competition binding experiments.     

c-Ha-ras-1 alleles in bladder cancer,Wilms' tumour and malignant melanoma

Summary Polymorphism of the human c-Ha-ras-1 gene has been analysed in DNA from 168 individuals using the enzymes MspI and HpaII. In all, 35 bladder cancer patients, 28 melanoma patients, 22 Wilms' tumour patients, 24 first-degree relatives of Wilms' tumour or melanoma patients and 59 unaffected controls were studied. A total of 13 different fragment sizes was detected, 4 common and 9 unusual. Of the latter, 4 were observed only in cancer patients or their first-degree relatives. The frequency of unusual alleles was significantly greater in bladder cancer patients and in the combined tumour group than in controls, thus providing support for the association of unique Ha-ras alleles and cancer. Some unaffected relatives of patients carried unusual alleles, and thus there is no absolute relationship between Ha-ras genotype and disease.     

Control and manipulation of gene expression during tomato fruit ripening

Ripening is a complex developmental process involving changes in the biochemistry, physiology and gene expression of the fruit. It is an active process characterised by changes in all cellular compartments. cDNA cloning has been used as an approach to analyse changes in gene expression during fruit ripening. This has revealed that several genes are switched on specifically during fruit ripening, including one encoding polygalacturonase (PG), a major cell wall protein. These cDNA clones have been used to study the expression of the genes in normal and ripening mutant fruits, and under environmental stress conditions.The PG gene has been isolated and it has been demonstrated that 1450 bases 5 of the coding region are sufficient for the tissue- and development-specific expression of a bacterial marker gene in transgenic tomatoes. Antisense RNA techniques have been developed to generate novel mutant tomatoes in which the biochemical function of this enzyme and its involvement in fruit softening has been tested.     

Treatment of experimental allergic encephalomyelitis with myelin basic protein: Which route is best?

When myelin basic protein (BP) has been used for the treatment of multiple sclerosis (MS), it has been injected intramuscularly (IM) or subcutaneously (SC). Experimental allergic encephalomyelitis (EAE) is widely used as a model for MS, and the use of BP for MS is based on its efficacy in EAE. The present work shows that BP is more effective in EAE when administered by intravenous (IV) route than by IM or SC routes. These observations may be pertinent to therapeutic trials in MS.Special Issue dedicated to Dr. Elizabeth Roboz-Einstein.     

Functional morphology of embryonic development in the Port Jackson shark Heterodontus portusjacksoni (Meyer)

The oviparous Port Jackson shark Heterodontus portusjacksoni embryo has a long incubation of 10–11 months during which it undergoes major morphological changes. Initially the egg capsule is sealed from the external environment by mucous plugs in either end of the capsule. Four months into incubation, the egg capsule opens to the surrounding sea water. Fifteen stages of development are defined for this species, the first 10 occur within the sealed capsule, the remaining five after capsule opening to hatching. The functional significance of major definitive characters such as circulation within the yolk membrane and embryo, rhythmic lateral movement of the embryo, external gill filaments, heart activity, internal yolk supplies, egg jelly and the significance of the opening of the egg capsule are described. The egg jelly in the sealed capsule functions to mechanically protect the embryo during early development, however, it eventually creates a hypoxic environment to the embryo as the available oxygen is used up. This generates several physiological challenges to the developing embryo. It is able to overcome these problems by morphological changes such as increasing the effective surface area for gaseous exchange with the development of external gill filaments, fins and extensive circulation in both the embryo and attached external yolk sac. These adaptations become limiting as the embryo grows and respiratory needs outweigh the available oxygen. At this time, the mucous plugs dissolve and the capsule becomes open to the external environment.     

The effects of powdered carp pituitary on ovarian development, ovarian ascorbic acid and ovulation in Carassius carassius L. exposed to various photoperiod and temperature regimes

The effects of temperature, photoperiod and powdered carp pituitary on ovarian development (measured by change in diameter of intraovarian eggs and gonadosomatic index), ovulation and ovarian ascorbic acid have been studied in crucian carp in winter. Short photoperiods stimulated ovarian development but long photoperiods were inhibitory. Photoperiod seemed to exert this effect by altering the release of pituitary gonadotropin. Temperature affected ovarian development independently of photoperiod. High temperatures were stimulatory and overcame the negative effect of a long photoperiod. The results suggested that temperature acts at the level of the gonad rather than the pituitary. On the basis of these findings a hypothesis is suggested to explain gonadal cycles in cyprinids and similarities to previous findings in other fish groups are discussed.
Levels of ovarian ascorbic acid varied according to treatments. Ovulation was associated with a decreased level. The results suggested that this vitamin aids biosynthesis of sex steroids in a similar fashion to that observed in higher animals. The results also demonstrated that measurement of gonadal ascorbic acid can provide a useful indication of physiological events at the level of the gonad.