The use of two-dimensional gradient plates in determining the responses of non-sulphur purple bacteria to pH and NaCl concentration

Abstract Chemical gradients can easily be established in agar gels to test behaviour of bacteria in respect to two variables. Agar plates with pH and NaCl gradients have provided a simple technique for useful comparison of heterotrophic bacteria and the present paper extends observations to non-sulphur purple photosynthetic bacteria.     

Parallel responses of bees to Pleistocene climate change in three isolated archipelagos of the southwestern Pacific

The impacts of glacial cycles on the geographical distribution and size of populations have been explored for numerous terrestrial and marine taxa. However, most studies have focused on high latitudes, with only a few focused on the response of biota to the last glacial maximum (LGM) in equatorial regions. Here, we examine how population sizes of key bee fauna in the southwest Pacific archipelagos of Fiji, Vanuatu and Samoa have fluctuated over the Quaternary. We show that all three island faunas suffered massive population declines, roughly corresponding in time to the LGM, followed by rapid expansion post-LGM. Our data therefore suggest that Pleistocene climate change has had major impacts across a very broad tropical region. While other studies indicate widespread Holarctic effects of the LGM, our data suggest a much wider range of latitudes, extending to the tropics, where these climate change repercussions were important. As key pollinators, the inferred changes in these bee faunas may have been critical in the development of the diverse Pacific island flora. The magnitude of these responses indicates future climate change scenarios may have alarming consequences for Pacific island systems involving pollinator-dependent plant communities and agricultural crops.     

The response of the hypothalamo-gonadal system to environmental factors in the zebra finch,Poephila guttata castanotis

Summary Studies of the hypothalamo-gonadal response of the zebra finch (Poephila guttata castanotis) to environmental factors were conducted by the use of adult birds captured in arid regions of South Australia. In these birds breeding activity is not photoperiodically induced but follows rainfall. The hypothalamo-hypophysial system participating in this response involves centres of the rostral and mediobasal (tuberal) hypothalamus. Parvocellular neurones in both hypothalamic portions are arranged in clusters. In the rostral hypothalamus magnocellular neurosecretory perikarya are spatially closely associated with the clusters which contain different types of parvocellular peptidergic neurones. Extended, complex neuropile formations, rich in synapses, encompass the neuronal clusters and provide important loci of neural-neuroendocrine interaction.Experiments were undertaken to correlate indicators of breeding activity, such as increased size and mass of testes, spermatogenesis, and plasma levels of androgens and luteinizing hormone, with a greater availability of drinking water, increased air humidity, and green vegetation, all of which follow rainfall. Birds maintained in male/female pairs in controlled-environment rooms at 27° C on 14L10D received a diet of seeds (containing 10% water). Thirty-two birds were given drinking water at a basal level of 1 ml/week and one of eight different treatments, consisting of different combinations of drinking water, relative air humidity, and green grass, for two weeks (4 males/treatment). The size of the left testis was estimated at laparotomy and blood samples were taken from a wing vein before and after treatment. The observations suggest that, in moisture-deprived (1 ml water/week) adult zebra finches, an increase in testicular size is associated with a free supply of water; synergistic effects of supplying both water and green grass, or water and high humidity, were also observed. However, in six other groups (8–16 males/treatment), receiving a higher basal level of water (access for 3 min/day), an increase in testicular mass was associated with high humidity, while smaller non-significant increases followed the provision of free water or green grass. Spermatogenic activity was not significantly correlated with testicular size or mass. Leydig cells were sparse in all groups. Plasma androgen levels and luteinizing hormone levels were not obviously correlated with the treatments and were lower than values in zebra finches breeding in outdoor aviaries.According to K.C. Parkes; see Note on Taxonomy, p. XVII, Avian Biology, Vol. IV (D.S. Farner, J.R. King, eds.), Academic Press, New York/London, 1974. Taeniopygia guttata castanotis is widely used for this subspecies in non-taxonomic literature.     

The influence of environmental factors on the spatial distribution of saxicolous lichens in a Norwegian coastal community

Abstract. The effects of vegetation cover, radiation, micro‐habitat variables and maritime influence on the floristic composition of a saxicolous community in Vingen, western Norway were studied. Particular emphasis is put on the local distribution of Fuscidea cyathoides, Ochrolechia tartarea, Ophioparma ventosa and Pertusaria corallina. Very little of the variation in the lichen community composition is directly related to measured micro‐environmental variables but variance partitioning shows that vegetation cover explains more of the floristic variation than radiation, maritime influence and microhabitat variables. Logistic regression analyses nevertheless indicate that the micro‐environment influences the spatial distribution of the four species. The high fraction of unexplained floristic variation, 91%, is suggested to result from (1) lack of fit of data to the response model; (2) some influential environmental variables that have not been recorded; (3) local historical factors that affect present day distribution and/or (4) apparent randomness in colonization. The results also agree with the view that the four lichen species in this study are able to co‐exist in the long‐term because of different spatial distributions resulting from different strategies with respect to ecology, dispersion and interaction.     

Migration and the effect of three environmental factors on the pre-reproductive period of the cotton-boliworm moth, Helicoverpa armigera

ABSTRACT. Migration by noctuid moths generally occurs while the adults are sexually immature, and so the pre-reproductive period provides an indication of the time available for migratory flight. Helicoverpa armigera (Hb.) (Lepidoptera: Noctuidae) is considered to be a facultative migrant, emigrating in response to a deterioration in local environmental conditions for adult survival and larval development; hence the effects of temperature, vapour-pressure deficit and the availability of sugar solution on the duration of the pre-reproductive period are investigated. Temperatures below 28^oC lengthened female pre-reproductive periods but, contrary to the findings of Isley (1935) for Helicoverpa zea (Boddie), temperatures above 28^oC shortened them. Females maintained at a vapour-pressure deficit of 23.7 ± 0.5 mmHg (c. 12% r.h.) and 6.45 ±0.15mmHg (c. 76% r.h.) did not have significantly different pre-reproductive period distributions. The availability of 10% w/v sugar solution (provided ad libitum ) had a marked effect on both the survival and the pre-reproductive period of both sexes. Moths given water for four nights followed by sugar solution thereafter, took significantly longer to reach reproductive maturity than those given sugar solution from emergence. Survival to reproductive maturity of moths given water only throughout their lives was poor (c. 20%). The significance of these findings to the migratory behaviour of H. armigera is discussed.     

Differences in the immunoreactivity to phenylethanolamine-N-methyltransferase in the central adrenergic neurons of four strains of rats

Summary Immunocytochemistry was used to compare the immunoreactivity of adrenergic neurons to a well characterized specific immunoserum to phenylethanolamine-N-methyltransferase (PNMT) in different strains of rats commonly used in research studies. In adult animals, marked differences were found in the PNMT-immunoreactivity of neurons between Wistar rats and other strains, resulting in a lower PNMT-immunostaining intensity (i) within neuronal perikarya of the medulla oblongata, and (ii) more strikingly, within nerve fibers and terminals located in various brain regions. This low PNMT-immunoreactivity of nerve fibers was detected both in 14- and 35-day-old Wistar rats. On the other hand, the HPLC measurement of catecholamines, in particular of adrenaline in the hypothalamus and the medulla oblongata, did not show any difference between adult Wistar and Sprague-Dawley rats. These data suggest that the low PNMT-immunoreactivity observed in central adrenergic neurons of the Wistar rats is related to the poor recognition of the antigen by the PNMT-antibody used. Possibly, these nerve cells mainly display an isoform of the enzyme that is immunologically different from the PNMT contained within the adrenergic neurons of other rat strains.     

A western blot assay to measure cyclin dependent kinase activity in cells or in vitro without the use of radioisotopes

We developed a quantitative method to measure the activity of cyclin-dependent kinases (Cdks) by western blotting, without radioisotopes. We prepared a recombinant protein substrate based upon the natural Cdk1 substrate, PP1Cα. By combining this substrate in a western blot method using fluorochrome based antibodies and phospho-imager analysis, we measured the K_m of ATP binding to Cdk1 to be 3.5 μM. We then measured Cdk1 activity in cell extracts from interphase or mitotic cells, and demonstrated that previously identified Cdk inhibitors could be detected by this assay. Our data show that we have a safe, reliable assay to identify Cdk1 inhibitors and measure Cdk1 activity.     

Case studies on the use of biotechnologies and on biosafety provisions in four African countries

This review is based on a study commissioned by the European Commission on the evaluation of scientific, technical and institutional challenges, priorities and bottlenecks for biotechnologies and regional harmonisation of biosafety in Africa. Biotechnology was considered within four domains: agricultural biotechnologies (‘Green’), industrial biotechnologies and biotechnologies for environmental remediation (‘White’), biotechnologies in aquaculture (‘Blue’) and biotechnologies for healthcare (‘Red’). An important consideration was the decline in partnerships between the EU and developing countries because of the original public antipathy to some green biotechnologies, particularly genetically modified organisms (GMOs) and food from GM crops in Europe. The study focus reported here was West Africa (Ghana, Senegal, Mali and Burkina Faso).The overall conclusion was that whereas high-quality research was proceeding in the countries visited, funding is not sustained and there is little evidence of practical application of biotechnology and benefit to farmers and the wider community. Research and development that was being carried out on genetically modified crop varieties was concentrating on improving food security and therefore unlikely to have significant impact on EU markets and consumers. However, there is much non-controversial green biotechnology such as molecular diagnostics for plant and animal disease and marker-assisted selection for breeding that has great potential application. Regarding white biotechnology, it is currently occupying only a very small industrial niche in West Africa, basically in the sole sector of the production of liquid biofuels (i.e., bio-ethanol) from indigenous and locally planted biomass (very often non-food crops). The presence of diffused small-scale fish production is the basis to develop and apply new (Blue) aquaculture technologies and, where the research conditions and the production sector can permit, to increase this type of production and the economy of this depressed areas. However, the problems bound to environmental protection must not be forgotten; priority should be given to monitor the risks of introduction of foreign species. Red biotechnologies potentially bring a vast domain of powerful tools and processes to achieve better human health, most notably improved diagnostics by molecular techniques, better targeting of pathogens and a better knowledge of their sensitivities to drugs to permit better treatment.Biosafety regulatory frameworks had been initiated in several countries, starting with primary biosafety law. However, disparate attitudes to the purpose of biosafety regulation (e.g., fostering informed decision-making versus ‘giving the green-light for a flood of GMOs’) currently prevent a needed consensus for sub-regional harmonisation. To date, most R&D funding has come from North America with some commercial interests from Asia, but African biotechnology workers expressed strong desire for (re-)engagement with interested parties from the European Union. Although in some of the visited countries there are very well qualified personnel in molecular biology and biosafety/regulation, the main message received is that human resources and capacity building in-house are still needed. This could be achieved through home-based courses and capacity-building including funds for post-degree research to motivate and retain trained staff.     

The mapping of three subfractions of endoplasmic reticulum membranes isolated from L-929 cells by the use of spin probes

Summary This paper concerns the estimation of microviscosity parameters in smooth, light rough and heavy rough endoplasmic reticulum subfractions isolated from L-929 cells. Electron spin resonance using three probes was utilized in order to make estimations of rotational correlation times. The highest microviscosity was found in the smooth fraction. The lipid bilayer is less viscous and the annular one more rigid in heavy rough compared to light rough membranes. The individual membrane subfractions differ with regard to their portrait of thermoinduced structural transitions. The highest number of such transitions was detected in smooth membranes. There were no low-temperature transitions (relative to physiological temperature) or common thermoinduced structural rearrangements of the lipids in the heavy rough subfraction, a membrane fraction characteristic of transformed cells. The results show that each membrane subfraction is characterized by an intrinsic series of thermoinduced structural transitions, which, in combination with an estimation of microviscosity, yields a portrait of the structural state of the membrane lipids.     

Differing responses of the two forms of photosystem II carbonic anhydrase to chloride, cations, and pH

The effects of Cl⁻, Mn²⁺, Ca²⁺, and pH on extrinsic and intrinsic photosystem II carbonic anhydrase activity were compared. Under the conditions of our in vitro experiments, extrinsic CA activity, located on the OEC33 protein, was optimum at about 30 mM Cl⁻, and strongly inhibited above this concentration. This enzyme is activated by Mn²⁺ and stimulated somewhat by Ca²⁺. The OEC33 showed dehydration activity that is optimum at pH 6 or below. In contrast, intrinsic CA activity found in the PSII complex after removal of extrinsic proteins was stimulated by Cl⁻ up to 0.4 M. Ca²⁺ appears to be the required cofactor, which implies that the location of the intrinsic CA activity is in the immediate vicinity of the CaMn₄ complex. Up to now, intrinsic CA has shown only hydration activity that is nearly pH independent.     

Stomatal responses of pearl millet (Pennisetum americanum [L.] Leeke) to leaf water status and environmental factors in the field

Abstract. Factors affecting stomatal conductance (g₁) of pearl millet ( Pennisetum americanum [L.] Leeke), cultivar BJ 104, were examined in the field in India during the dry season.
Diurnal changes in g₁ were evaluated for upper expanded leaves at flowering on two occasions using plants subjected to varying degrees of water stress. Except for the most severely stressed treatment, diurnal changes in g₁ closely matched changes in irradiance ( I ), the promotive effect of which largely overcame opposing influences on g₁ of increasing atmospheric vapour pressure deficit, and decreasing leaf water and turgor potentials (Ψ, Ψ_p).
Two main effects of water stress on g₁ were evident: (i) a decrease in the amplitude of the mid-day peak in g₁, and (ii) a decrease in the time over which high g₁ was maintained, resulting in early (mid-day) closure and hysteresis in the relationship between g₁ and I .
Leaf conductance was greatest for upper leaves and decreased down the canopy. At equivalent depths in the canopy g₁ was higher in flowering than in photoperiodically-retarded plants of the same age. The magnitude of water stress-induced stomatal closure increased down the plant, and was more marked in retarded than in flowering plants.
Within individual stress treatments Ψ of upper leaves decreased linearly as transpiration flux increased. It is concluded that stomatal behaviour of upper leaves of pearl millet at flowering largely operates to maximize assimilation rather than to minimize water loss.     

The novel chelator lipid 3(nitrilotriacetic acid)-ditetradecylamine (NTA3-DTDA) promotes stable binding of His-tagged proteins to liposomal membranes: Potent anti-tumor responses induced by simultaneously targeting antigen, cytokine and costimulatory signals to T cells

Recent studies indicate that the chelator lipid nitrilotriacetic acid ditetradecylamine (NTA-DTDA) can be used to engraft T cell costimulatory molecules onto tumor cell membranes, potentially circumventing the need for genetic manipulation of the cells for development of cell- or membrane-based tumor vaccines. Here, we show that a related lipid 3(nitrilotriacetic acid)-ditetradecylamine (NTA₃-DTDA, which has three NTA moieties in its headgroup instead of one) is several-fold more effective than NTA-DTDA at promoting stable His-tagged protein engraftment. IAsys biosensor studies show that binding of His-tagged B7.1 (B7.1-6H) to NTA₃-DTDA-containing membranes, exhibit a faster on-rate and a slower off-rate, compared to membranes containing NTA-DTDA. Also, NTA₃-DTDA-containing liposomes and plasma membrane vesicles (PMV) engrafted with B7.1-6H and CD40-6H exhibit greater binding to T cells, in vitro and in vivo. Engrafted NTA₃-DTDA-containing PMV encapsulated cytokines such as IL-2, IL-12, GM-CSF and IFN-γ, allowing targeted delivery of both antigen and cytokine to T cells, and stimulation of antigen-specific T cell proliferation and cytotoxicity. Importantly, use of B7.1-CD40-engrafted PMV containing IL-2 and IL-12 as a vaccine in DBA/2J mice induced protection against challenge with syngeneic tumor cells (P815 mammary mastocytoma), and regression of established tumors. The results show that stable protein engraftment onto liposomal membranes using NTA₃-DTDA can be used to simultaneously target associated antigen, costimulatory molecules and cytokines to T cells in vivo, inducing strong anti-tumor responses and immunotherapeutic effect.     

Boophilus microplus: the pattern of bovine immunoglobulin isotype responses to high and low tick infestations

Cattle present variable levels of resistance to ticks and the immune correlates of these heritable phenotypes must be known in order to develop effective vaccines. The antibody responses to tick salivary antigens were examined in cattle of tick-susceptible (Holstein) and tick-resistant (Nelore) breeds. After heavy infestations, levels of IgG1 and IgG2 antibodies decreased in Holsteins and remained the same in Nelores. Conversely, levels of IgE antibodies increased in Holsteins. Different sizes of tick burdens modulated the IgG1 antibody response in a susceptible breed (Aberdeen): levels were higher than in controls in heavily infested animals, but not in those undergoing intermediary or minimal infestations. The three experimental groups presented similar levels of IgG2 antibodies. Levels of IgE antibodies were higher only in animals undergoing intermediate infestations. These results indicate that tick infestations suppress the IgG antibody response in susceptible breeds, that IgE antibodies are not protective, and that the dose of tick saliva modulates the isotype of host antibody responses.     

The stacking of the thylakoids of two leguminosae. Differential responses to H+ and divalent cations

The stacking of the thylakoids of lupine and horse bean has been studied by the digitonin method in relation to the concentration of H⁺, Ca²⁺ or Mg²⁺. (1) The isolectric point appears to be 4.7 for the two species. At this pH, Ca²⁺ has no effect on the stacking of the lupine thylakoids but it lowers the stacking of those of horse bean. (2) At pH 7.6, for any given Ca²⁺ concentration, the horse bean thylakoids fix a lesser amount of Ca²⁺ than those of lupine but they are more stacked. (3) The surface potential has been estimated by the use of the Gouy-Chapman model, modified to take account of H⁺ and Ca²⁺ binding. Simulation of the experiments indicates that the results may be explained by supposing that (i) the anionic groups are less numerous on the horse bean thylakoids than on those of lupine, (ii) they are arranged such that the affinity for the binding of Ca²⁺ or Mg²⁺ is higher for horse bean and virtually nil for lupine, and (iii) the divalent cation binding per se promotes the stacking when the coulombic repulsion is sufficiently weakened by screening and binding.     

The use and misuse of calcium carbonate as an aid to the spectrophotometric assay of phytochrome in vitro

Supernatant and resuspended pellet samples from a centrifugation of homogenised, etiolated oat seedlings were prepared and assayed spectrophotometrically for phytochrome in the presence and absence of added calcium carbonate (CaCO₃) particles under a variety of conditions. At a constant sample thickness, in the absence of CaCO₃, increasing sample concentration had no significant effect on the expected phytochrome reading. In the presence of CaCO₃, however, as sample concentration increased, the phytochrome reading was less than, expected more so in resuspended pellet samples than in supernatant samples. At a constant sample concentration in the absence of CaCO₃, increasing sample thickness gave no significant difference from the excepted phytochrome reading in supernatant samples, but led to a slight increase over the expected phytochrome reading in resuspended pellet samples. In the presence of CaCO₃, increasing sample thickness led to a drop from the expected phytochrome reading in both sample types, but more so in resuspended pellet samples. These findings show that the use of CaCO₃ as an aid to spectrophotometric phytochrome assay can lead to large artifacts in the instrument reading and that its use should be approached with caution.     

Effect of diet on the response in rats to lead acetate given orally or in the drinking water

Liver lead levels were higher for rats that were orally dosed with 100 mg lead acetate/kg body wt and fed a semipurified diet than those fed a pelleted diet. The activities of delta-aminolevulinic acid dehydratase in blood were decreased in the group given 10 μg lead acetate/mL in their drinking water and fed the semipurified diet, but not in the blood from the group treated with lead and fed the pelleted diet. The levels of glutathione in the liver decreased in response to lead acetate in the drinking water of rats fed the semipurified diet, but not in the livers from the group fed the pelleted diet and treated with lead. The levels of lead in the kidneys were higher in the group given lead acetate in their drinking water and fed the semipurified diet than in the lead treated group fed the pelleted diet. Rats dosed orally with lead or given lead in the drinking water and fed the semipurified diet were more sensitive to lead treatment than those fed the pelleted diet.     

Differential responses of three fungal species to environmental factors and their role in the mycorrhization of<Emphasis Type="Italic"> Pinus radiata</Emphasis> D. Don

Three ectomycorrhizal (ECM) isolates of Rhizopogon luteolus, R. roseolus and Scleroderma citrinum were found to differ markedly in their in vitro tolerance to adverse conditions limiting fungal growth, i.e. water availability, pH and heavy metal pollution. S. citrinum was the most sensitive, R. luteolus intermediate and R. roseolus the most tolerant species. Pinus radiata D. Don seedlings were inoculated in the laboratory and in a containerised seedling nursery with spore suspensions of the three ECM species. Colonisation percentage was considerably lower under nursery conditions, probably due to competition by native fungi. The effects of nursery ECM inoculation on seedling growth depended on the fungal species. Only R. roseolus-colonised plants showed a significantly higher shoot growth than non-mycorrhizal plants. All three fungi induced significantly higher root dry weights relative to control plants. Despite the low mycorrhizal colonisation, mycorrhization with all three species improved the physiological status of nursery-grown seedlings, e.g. enhanced root enzyme activity, shoot nutrient and pigment content, net photosynthesis rate and water use efficiency. Of the three fungal species, R. roseolus was the most effective; this species was also the most adaptable and showed the greatest range of tolerance to adverse environmental conditions in pure culture. It is, therefore, proposed as a promising fungal species for ECM inoculation of P. radiata in the nursery.