Effects of growth hormone and hypophysectomy of pregnant rats on serum concentrations of pregnancy-associated murine protein-1

Continuous infusion of bovine GH to hypophysectomized non-pregnant rats increased serum concentrations of pregnancy-associated murine protein-1 (PAMP-1) to the levels of adult female rats and pregnant rats. Serum concentrations of PAMP-1 were followed from Day 16 of gestation until 3 days after parturition in hypophysectomized (on Day 14 of gestation) and intact pregnant rats. In the intact pregnant rat there was a decrease in PAMP-1 values from Day 16 until delivery. The serum concentrations of PAMP-1 in hypophysectomized pregnant rats were similar to those in intact pregnant rats before parturition, but PAMP-1 concentrations decreased markedly after parturition in the hypophysectomized rats. We suggest that the serum concentrations of PAMP-1 can be maintained without pituitary GH in late pregnancy, while serum values of PAMP-1 in non-pregnant rats is dependent upon a continuous secretion of pituitary GH.     

Use of leaky nitrate reductase-deficient mutants of tomato (Lycopersicon esculentum Mill.) for selection of somatic hybrid cell lines with wild type potato (Solanum tuberosum L.)

Protoplasts of two leaky nitrate reductase deficient and thus nitrate auxotrophic (NAR) mutants of tomato and their wild types, were fused with protoplasts of monoploid potato. In all four combinations hybrid calli grew more vigorously than parental calli and this somatic hybrid vigour as such provided a useful enrichment for somatic hybrids. Selection against nitrate auxotrophy further increased the efficiency of the enrichment, particularly if a molybdenum cofactor mutation was used as the basis for the selection. It is concluded that the nitrate auxotrophy of these NAR mutants is sufficiently expressed at the level of the cell, to allow its use in somatic hybridization experiments with potato.     

A review of <Emphasis Type="Italic">Solanum mauritianum</Emphasis> biocontrol: prospects,promise and problems: a way forward for South Africa and globally

The invasive tree Solanum mauritianum Scopoli remains one of the world’s most widespread environmental weeds. Despite biocontrol providing one of the few viable long-term solutions to tackling S. mauritianum invasions globally, only South Africa and, more recently, New Zealand, have programmes in place. Ongoing biocontrol efforts against S. mauritianum are reviewed here with particular reference to South Africa. The South African programme has suffered a troubled history, with considerable research efforts culminating in the eventual release and establishment of only two insect agents, Gargaphia decoris Drake and Anthonomus santacruzi Hustache. The difficulties experienced have hindered research into new agents, causing apprehension in using biocontrol internationally. However, recent studies have demonstrated that biocontrol may be deserving of renewed investment, particularly within an integrated management context. In this review, we advocate for the revival of the S. mauritianum biocontrol programme in South Africa, and discuss possible avenues for future research internationally.     

Discovering the intelligence in molecular biology

The Third International Conference on Intelligent Systems in Molecular Biology was truly an outstanding event. Computational methods in molecular biology have reached a new level of maturity and utility, resulting in many high-impact applications. The success of this meeting bodes well for the rapid and continuing development of computational methods, intelligent systems and information-based approaches for the biosciences. The basic technology, originally most often applied to ‘feasibility’ problems, is now dealing effectively with the most difficult real-wold problems. Significant progress has been made in understanding protein-structure information, structural classification, and how functional information and the relevant features of active-site geometry can be gleaned from structures by automated computational approaches. The value and limits of homology-based methods, and the ability to classify proteins by structure in the absence of homology, have reached a new level of sophistication. New methods for covariation analysis in the folding of large structures such as RNAs have shown remarkably good results, indicating the long-term potential to understand very complicated molecules and multimolecular complexes using computational means. Novel methods, such as HMMs, context-free grammars and the uses of mutual information theory, have taken center stage as highly valuable tools in our quest to represent and characterize biological information. A focus on creative uses of intelligent systems technologies and the trend toward biological application will undoubtedly continue and grow at the 1996 ISMB meeting in St Louis.     

Activation of G-Proteins with AlF4Induces LFA-1-Mediated Adhesion of T-Cell Hybridoma Cells to ICAM-1 by Signal Pathways That Differ from Phorbol Ester- and Manganese-Induced Adhesion

T-cell hybridomas metastasize widely, and the extent of dissemination correlates with invasiveness in fibroblast cultures. Previously, we provided evidence that both metastasis andin vitroinvasion require activation of LFA-1, induced by G-protein-transduced signals triggered by as yet unidentified factors. We show here that LFA-1-mediated adhesion of TAM2D2 T-cell hybridoma cells to ICAM-1 can in fact be induced by direct activation of G-proteins using AlF⁻₄, to the same extent as by using PMA or Mn²⁺. We assessed effects of protein kinase C (PKC), tyrosine kinase (TK), PI3-kinase (PI3K), and phospholipase C (PLC) inhibitors. Both AlF⁻₄-induced adhesion and invasion were completely blocked by the TK inhibitor genistein and partially blocked by the PI3K inhibitor wortmannin, but not influenced by PKC inhibitor GF109203X. Downregulation of PKC did not affect invasion or adhesion induced by AlF⁻₄either. In contrast, GF109203X and PKC downregulation blocked PMA-induced adhesion, but genistein and wortmannin had no effect. Invasion and both AlF⁻₄- and PMA-induced adhesion were completely blocked by the PLC inhibitor U73122. Mn²⁺-induced adhesion, which was not or was only partially blocked by the other inhibitors, was delayed by U73122, and spreading of Mn²⁺-treated cells was completely prevented by U73122. However, PLC activity during adhesion was not detected. We conclude that signals required for invasion and G-protein-induced adhesion are similar and are distinct from PKC-induced adhesion, and that in all cases PLC is likely to be activated, but is probably too local and/or transient to be detected.     

Three-Dimensional Reconstruction of a Collagen IV Analogue in the Dogfish Egg Case Wall

The wall of the egg case of the dogfish (Scyliorhinus canicula) contains an analogue of collagen Types IV and VIII organised into a regular 3-dimensional network. It presumably provides both a protective and a filtering role for the eggs contained within it. Electron micrographs of longitudinal and transverse sections, including systematically tilted sections, have been used both to define, for the first time, the space group symmetry of the lattice and to carry out 3-D reconstruction of the unit cell contents. This cell was found to be tetragonal, space group I422, with a = b = 11 ± 1 nm, and c = 74 ± 4 nm. Consistent with this, projection symmetries were c2mm for the [1,0,0] view, p2mm for the [1,1,0] view, and p4mm for the projection down the c axis (the [0,0,1] view), and all observed reflections in the computed Fourier transform obeyed the ruleh+k+l= 2n(ninteger) for body-centred lattices. The 3-D reconstruction, the first electron micrograph 3-D reconstruction of a collagen-containing material, is interpreted in terms of variations of previous molecular models for this structure. Type IV collagen is a constituent of the basal lamina, where it forms a network with both structural and filtering properties. The dogfish egg case structure may throw light on the (less regular) collagen IV structure of the basal lamina.     

Of feathers and fur: Differential pollinator roles of birds and small mammals in the grassland succulent Aloe peglerae

The pollination syndrome of the genus Aloe, with gaudy inflorescences and orange–red flowers, suggests bird pollination. However, the diversity of flowering phenologies and structures suggests that generalizations within the group are currently uninformative because few studies have addressed the role of multiple pollinator guilds, especially mammals. Aloe peglerae, endemic to montane grassland of the Magaliesberg Mountains, South Africa, is primarily bird pollinated, although small mammals are recorded nocturnal visitors. We compared the independent contributions of diurnal and nocturnal visitors, i.e. birds and small mammals respectively, to reproductive success by assigning 12 flowering A. peglerae plants to each of four pollinator selective exclusion treatments: (i) no‐visitors; (ii) nocturnal‐visitors; (iii) diurnal‐visitors; and (iv) all‐visitors (control). Birds alone contributed more to fruit set (1.2–2.6 times), average seed/fruit (1.0–1.8 times) and total seed production (1.1–2.8 times) than both the all visitors (birds and small mammals combined) and the small mammal visitors respectively. The exclusion of all visitors resulted in no fruit set, suggesting that A. peglerae requires pollinators to set seed. Germination trials over six weeks and viability testing with tetrazolium staining identified no significant differences among the three treatments that produced fruit and seed. Germination success was 90–97%, indicating that seed quality of small‐mammal and bird‐pollinated plants are similar. Aloe peglerae inflorescences were visited continuously throughout the day and night, with the Cape rock‐thrush (Monticola rupestris) and dark‐capped bulbul (Pycnonotus tricolor) being the most abundant pollinators, accounting for 68.2% and 13.7% of all visits respectively in the control treatment. Small mammals, i.e. Namaqua rock mouse (Micaelamys namaquensis) and eastern rock sengi (Elephantulus myurus), while not increasing reproductive success in the absence of birds, are suitable alternative pollinators. The presence of diurnal bird and nocturnal small mammal visitors provides a diversity of pollinators in this resilient pollination syndrome.     

Variability in the area,energy and time costs of wintering waders responding to disturbance

Birds’ responses to human disturbance are interesting due to their similarities to anti‐predator behaviour, and understanding this behaviour has practical applications for conservation management by informing measures such as buffer zones to protect priority species. To understand better the costs of disturbance and whether it will impact on population size, studies should quantify time‐related responses as well as the more commonly reported flight initiation distance (FID). Using waders wintering on an estuarine area, we experimentally disturbed foraging birds on the Wash Embayment, UK, by walking towards them and recording their responses (FID, alert time, time spent in flight, time taken to resume feeding, and total feeding time lost). We present data for 10 species of conservation concern: Curlew Numenius arquata, Oystercatcher Haematopus ostralegus, Bar‐tailed Godwit Limosa lapponica, Grey Plover Pluvialis squatarola, Redshank Tringa totanus, Knot Calidris canutus, Turnstone Arenaria interpres, Ringed Plover Charadrius hiaticula, Sanderling Calidris alba and Dunlin Calidris alpina. Larger species responded more strongly, response magnitude was greater under milder environmental conditions, and responses varied over both small and large spatial scales. The energetic costs of individual responses, however, were low relative to daily requirements and disturbance events were unlikely to be frequent enough to seriously limit foraging time. We suggest, therefore, that wintering wader populations on the Wash are not currently significantly negatively impacted by human disturbance during the intertidal foraging period. This is also likely to be the case at other estuarine sites with comparable access levels, visitor patterns, invertebrate food availability and environmental conditions.     

Finding needles in a genomic haystack: targeted capture identifies clear signatures of selection in a nonmodel plant species

Teasing apart neutral and adaptive genomic processes and identifying loci that are targets of selection can be difficult, particularly for nonmodel species that lack a reference genome. However, identifying such loci and the factors driving selection have the potential to greatly assist conservation and restoration practices, especially for the management of species in the face of contemporary and future climate change. Here, we focus on assessing adaptive genomic variation within a nonmodel plant species, the narrow‐leaf hopbush (Dodonaea viscosa ssp. angustissima), commonly used for restoration in Australia. We used a hybrid‐capture target enrichment approach to selectively sequence 970 genes across 17 populations along a latitudinal gradient from 30°S to 36°S. We analysed 8462 single‐nucleotide polymorphisms (SNPs) for F_ST outliers as well as associations with environmental variables. Using three different methods, we found 55 SNPs with significant correlations to temperature and water availability, and 38 SNPs to elevation. Genes containing SNPs identified as under environmental selection were diverse, including aquaporin and abscisic acid genes, as well as genes with ontologies relating to responses to environmental stressors such as water deprivation and salt stress. Redundancy analysis demonstrated that only a small proportion of the total genetic variance was explained by environmental variables. We demonstrate that selection has led to clines in allele frequencies in a number of functional genes, including those linked to leaf shape and stomatal variation, which have been previously observed to vary along the sampled environmental cline. Using our approach, gene regions subject to environmental selection can be readily identified for nonmodel organisms.     

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C₃ grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C₄ grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.