Coordinated action of pectinesterase and polygalacturonate lyase complex of Clostridium multifermentans.

The polygalacturonate lyase and pectinesterase activities of Clostridium multifermentans, both produced extracellularly when the organism grows on pectin or polygalacturonate, have been suggested to be associated in a single complex. Both enzymic sites act on their respective substrates by single-chain action patterns, as shown by equivalent release of terminal tritium label and total product throughout the reaction. From these results, the Km and V of the lyase, and the amount of lyase activity present, we calculate the steady-state concentration of lyase substrate expected during action of the two sites on pectin if the sites are independent. No such steady-state concentration of lyase substrate was observed. Therefore, we conclude that the two types of active site act in a coordinated manner; the polysaccharide chain passes from the esterase site to the lyase site without intermediate dissociation and rebinding. This 'molecular disassembly line' constituted by the two sites may represent a system of general significance in synthesis and degradation of biological polymers.     

Mandibular movements and their control inHomarus gammarus

Summary The skeletal morphology, musculature and innervation of the mandible of the common lobster,Homarus gammarus, are described as a basis for the functional study included in the two subsequent papers.Although the mandible articulation takes the form of a hinge with movement in a single plane, the musculature of the mandible is complex. The main muscles are similar to those ofAstacus (Schmidt, 1915) but some smaller, previously undescribed muscles were found.As forAstacus (Keim, 1915) andCambarus (Chaudonneret, 1956) the mandibular muscles are innervated by two nerve trunks, the inner and outer mandibular nerves. However, differences occur in the branching of these nerves and the muscles which they innervate.A group of sensory cells associated with the posterior stomach nerve (omn 4) are described. It is suggested that these form a proprioceptive organ associated with the hypodermis overlying the lateral mandible articulation.An interesting group of neurones lying at the confluence of nerve branches from omn 2, omn 3, and omn 4 is described.     

The structure and growth of the statocyst in the Australian crayfish Cherax destructor

The morphology of the statocyst of the Australian crayfish Cherax destructor was examined using scanning electron microscopy. It resembles in general structure, size, and position the statocysts of crayfish described previously, and the size and distribution of the fields of setae on the floor of the capsule are similar but not the same. Over the size range examined, the relationship between the carapace length, the length of the basal antennular segment, the diameter of the statocyst capsule, and the total number of setae are all linear. The number and position of setae on the floor of the statocyst capsule were mapped for animals in two size classes (small, ca. 20 mm; large, ca. 50 mm) to test for changes in their arrangement during growth. The change in the ratio of setal number to statocyst size between the two size classes was about three times greater for the anterior setal field than for the other fields. We propose that differential development of the setal fields may be related to changes in the force-monitoring requirements of the animals as they increase in size, but this remains to be experimentally tested.     

Parathyroid hormone-related protein production in the lamprey <Emphasis Type="Italic">Geotria australis</Emphasis>: developmental and evolutionary perspectives

This study explored the distribution of parathyroid hormone-related protein (PTHrP) and its mRNA in tissues of the lamprey Geotria australis, a representative of one of the two surviving groups of an early and jawless stage in vertebrate evolution. For this purpose, antibodies to N-terminal and mid-molecule human PTHrP were used to determine the locations of the antigen. Sites of mRNA production were demonstrated by in situ hybridisation with a digoxigenin-labelled riboprobe to exon VI of the human PTHrP gene. The results revealed that antigen and its mRNA were widely distributed among similar sites of tissue localisation to those described for mammalian and avian species. However, some novel sites of localisation, such as in the gill and notochord, were also found. Some differences in PTHrP localisation were noted among individuals at different intervals of the life cycle, indicating that the distributions of PTHrP, and possibly its roles, change with the stage of development in this species. The widespread tissue distribution in G. australis implies diverse physiological roles for this protein. The presence of PTHrP in the lamprey, a representative of a group of vertebrates, which apparently evolved over 540 million years ago, strongly suggests that it is a protein of ancient origin. In addition, the successful use of antibodies and probes based on the human sequence in the lamprey also provides evidence that the PTHrP molecule may have been conserved from lampreys through to humans.     

Observations on the reproductive effects of once or twice weekly injections for 6 weeks of the GnRH agonist deslorelin in the cow

This study investigated the reproductive effects in Holstein-Friesian cows of once or twice weekly intramuscular injection for 6 weeks of 100 microg of the GnRH agonist deslorelin at intervals. Oestrus was synchronized in non-lactating Holstein-Friesian cows before they were allocated randomly to receive either 100 microg deslorelin once weekly (D1; N=10) or twice weekly (D2; N=8) or acted as untreated controls (CON; N=8). The first injection was given on day 6 post-oestrus and the last injection on day 48 post-oestrus. Blood samples were collected twice weekly from each cow until day 76 after the synchronized oestrus to profile plasma P4. A single injection of prostaglandin was administered to all cows on day 20 post-oestrus to ensure luteolysis occurred. Ovaries were examined twice weekly by transrectal ultrasonography and then subsequently at weekly intervals to monitor ovarian structures. Progesterone profiles observed over two complete cycles for CON cows were typical of those expected for cows displaying regular oestrous cycles. Injection of deslorelin on day 6 post-oestrus induced ovulation in 100% (18/18; D1 and D2) of deslorelin-treated cows. Three categories of responses based on plasma P4 profiles were defined amongst the deslorelin-treated cows. Complete anoestrus was observed in 20% (2/10) of D1 and 63% (5/8) of D2 cows. A partial response characterised by intermittently low concentrations of P4 was observed in 50% (5/10) of D1 and 25% (2/8) of D2. A complete lack of response to deslorelin, with P4 profiles indistinguishable from CON cows, was seen in 30% (3/10) of D1 and 13% (1/8) of D2 cows. When results from D1 and D2 were pooled, a greater proportion of deslorelin-treated cows had abnormal ovarian cycles during the treatment period (56% versus 0%; D1 and D2 versus CON, P <0.001). In conclusion, the repeated injection of deslorelin either once or twice weekly for 6 weeks significantly altered the ovarian cycles of some cows; individual cow responses observed varied widely and ranged from complete anoestrus to a cycle indistinguishable from normal.     

Should Health Professionals Screen All Women for Domestic Violence?

BACKGROUND TO THE DEBATE: The US and Canadian task forces on preventive health recently declared that there is not enough evidence to recommend for or against routine universal screening of women for domestic violence. Yet some experts argue that routine enquiry is justified.     

Reproductive responses of early postpartum dairy cattle to continuous treatment with a GnRH agonist (deslorelin) for 28 days to delay the resumption of ovulation

An experiment was conducted to investigate the potential of chronic delivery of a potent GnRH agonist (deslorelin) via subcutaneous implants to delay the resumption of ovulatory cycles in postpartum dairy cattle. Cows received either a single deslorelin implant (n=40; DES) within 7 days of calving or were untreated (n=24; CON). Blood samples were collected thrice weekly during the period the implants were in place. Plasma concentrations of progesterone (P4) and 17beta-oestradiol (E2) were measured along with selected serum metabolites. Implants were removed after 28 days and cattle monitored daily for behavioral oestrus. Serial weekly blood samples were collected to detect the occurrence of ovulation. Cows were artificially inseminated as they were detected in oestrus from 30 days after implant removal. Pregnancy status was subsequently determined by manual palpation of uterine contents at strategic intervals.Insertion of implants induced ovulation in 3/40 cows as determined by a rise in progesterone 7 days later. Deslorelin implants delayed the onset of ovulatory cycles compared with untreated herdmates (mean 43.4+/-4.2 versus 57.3+/-1.6 days postpartum; P<0.001). A noticeable delay of at least 12 days was observed between implant removal and the first animals ovulating. Mean plasma E2 concentrations during the period the implants were in place were similar for DES and CON cows that experienced a prolonged spontaneous postpartum anoestrus (low P4 >60 days), although both groups had concentrations only 20% of CON cows that had ovulated prior to 30 days postpartum.The patterns of recovery following implant removal were highly variable. A number of DES cows showed a low and transient rise in plasma progesterone around 21 days after implant removal. Some cows displayed oestrus but did not appear to form a fully functional corpus luteum with this phenomenon being more prevalent among DES cows (7 of 37 versus 1 of 21; P<0.05). Overall, significantly more DES cows were detected in oestrus without ovulating compared to CON cows. Final pregnancy rates did not differ between DES and CON groups. The mean time to conception for DES cows was longer (21.2+/-5.6 versus 41.1+/-7.4 days, CON versus DES; P<0.01). This difference was not present if the time from first ovulation to conception was compared (50.5+/-5.3 versus 43.5+/-9.3 days, CON versus DES; P>0.05). Deslorelin implants provided a reliable method of inducing anoestrus when treatment was initiated prior to 3 days postpartum. A variable pattern of recovery was observed which delayed conception but did not ultimately reduce the final proportion pregnant at the completion of mating. The study demonstrates the potential of GnRH agonists to control postpartum reproductive function to manipulate the fertility of dairy cows.     

Gibberellin A43 and other terpenes in endosperm of Echinocystis macrocarpa

By GC-MS the following acidic constituents of the endosperm of Echinocystis macrocarpa were identified: abscisic acid and its trans,trans-isomer, 4′-dihydrophaseic acid, GA₄, GA₇, iso-GA₇, GA₂₄, GA₂₅, two isomers of GA₁₃, GA₄₃, ent-6α,7α,17-trihydroxy-16αH-kauran-19-oic acid and ent-6α,7α, 16β, 17-tetrahydroxykauran- 19-oic acid. The structures of the last three new natural products were confirmed by partial synthesis. ent-Kaurene was detected in the neutral fraction.