Waterbird trapping and hunting in Lake Manzala,Egypt, with an outline of its economic significance

In the winters of 1978/79 and 1979/80, and in September and October 1980, the authors investigated the trapping and hunting of waterbirds in Lake Manzala (Egypt). It has been calculated that 98 000–162 000 waterbirds are killed annually. The number of people practising these activities is estimated at less than 2000 in a population of 35 000–40 000 fishermen. The majority of the birds are, however, taken by less than 100 men. Compared with 1930 about 30–50% fewer duck and coot are sold. This decrease is mainly caused by the decrease in numbers of pochard and tufted duck. Hunting pressure on waders was found to be extremely high. The contribution of these activities to the regional economy is reviewed and found to be insignificant. A number of conservation measures are recommended.     

The other side of the coin: A case study on the impact of financial autonomy on irrigation management performance in the Philippines

The paper assesses the impact of the removal of operating subsidies to the Philippine National Irrigation Administration on the management performance of a small canal irrigation system in Southern Luzon. It shows that in this case the creation of financial autonomy of the agency did not fully engender the often assumed positive effects regarding both accountability relationships and irrigation management performance. The conclusions specify a number of issues related to the theory of financial autonomy which require further study.     

Structural basis for the activation of cholera toxin by human ARF6-GTP

The Vibrio cholerae bacterium causes devastating diarrhea when it infects the human intestine. The key event is adenosine diphosphate (ADP)-ribosylation of the human signaling protein GSalpha, catalyzed by the cholera toxin A1 subunit (CTA1). This reaction is allosterically activated by human ADP-ribosylation factors (ARFs), a family of essential and ubiquitous G proteins. Crystal structures of a CTA1:ARF6-GTP (guanosine triphosphate) complex reveal that binding of the human activator elicits dramatic changes in CTA1 loop regions that allow nicotinamide adenine dinucleotide (NAD+) to bind to the active site. The extensive toxin:ARF-GTP interface surface mimics ARF-GTP recognition of normal cellular protein partners, which suggests that the toxin has evolved to exploit promiscuous binding properties of ARFs.     

Spectral dependence of photosynthesis and light absorptance in single leaves and canopy in rose

Little is known about the effects of leaf pigmentation (related to leaf ontogeny), on the spectral dependence of photosynthesis and most observations have been limited so far to single leaves. This study aimed to investigate photosynthesis and the related optical properties of two types of rose leaves, young reddish leaves and middle age green leaves, and to quantify the spectral dependence of photosynthesis at the canopy level.     

Pathogenicity and reproductive fitness of <Emphasis Type="Italic">Pratylenchus coffeae</Emphasis> and <Emphasis Type="Italic">Radopholus arabocoffeae</Emphasis> on Arabica coffee seedlings (<Emphasis Type="Italic">Coffea arabica</Emphasis> cv. Catimor) in Vietnam

The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128, and 256 nematodes per cm³ soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage model Y = m + (1-m).z^Pi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm³ soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of nematode numbers at 30 and 60 dai.     

Sensitivity of root pruned ‘Conference’ pear to water deficit in a temperate climate

The present study examines the need for irrigation in pear trees (Pyrus Communis, cv. ‘Conference’) under low evaporative demand conditions, like in Belgium, in order to maintain a consistent fruit yield and high fruit size. To determine the sensitivity of the pear yield under low evaporative demand conditions three different orchards were monitored. The study shows that a Ψ_soil of −60 kPa during shoot growth has no effect on fruit yield but lower Ψ_soil values induced a decline in both fruit size and total yield. Just as for arid environments a Ψ_stem of −1.5 MPa is related to negative yield responses. In dry conditions lower Ψ_soil and Ψ_stem values were observed in root pruned trees compared to not root pruned trees in the same irrigation treatment, however without yield decline. In one orchard a biannual bearing tendency was observed after root pruning. Furthermore intensive Ψ_soil measurements show a high variation in Ψ_soil between orchards, and within an orchard. This underlines the need for irrigation management on a parcel level and the need for new irrigation scheduling techniques which take the spatial variation in the orchard into account.     

Seasonal variations in the deoxypodophyllotoxin content and yield of Anthriscus sylvestris L. (Hoffm.) grown in the field and under controlled conditions

Deoxypodophyllotoxin (DPT) is the main lignan in Anthriscus sylvestris . For this study two sets of experiments with 16 plants and seeds, collected from a wide geographical range, were carried out. The DPT content in roots was significantly lower (p < 0.05) when the plants were cultivated in a non-native environment. For field-grown plants the highest DPT content was found in March (second year): 0.15% w/w (dry weight) in roots; 0.03% w/w in aerial parts. For plants grown in the climate room, the highest concentration (0.14% w/w) was observed in April (second year) in the roots and in July (first year) in the aerial parts (0.05% w/w). For the isolation of DPT, roots are the most suitable part. The best harvest times are March (second year) for outdoor plants and April (second year) for indoor plants when height content and adequate biomass give the optimal DPT yield.     

Anti-inflammatory activity of human IgG4 antibodies by dynamic Fab arm exchange

Antibodies play a central role in immunity by forming an interface with the innate immune system and, typically, mediate proinflammatory activity. We describe a novel posttranslational modification that leads to anti-inflammatory activity of antibodies of immunoglobulin G, isotype 4 (IgG4). IgG4 antibodies are dynamic molecules that exchange Fab arms by swapping a heavy chain and attached light chain (half-molecule) with a heavy-light chain pair from another molecule, which results in bispecific antibodies. Mutagenesis studies revealed that the third constant domain is critical for this activity. The impact of IgG4 Fab arm exchange was confirmed in vivo in a rhesus monkey model with experimental autoimmune myasthenia gravis. IgG4 Fab arm exchange is suggested to be an important biological mechanism that provides the basis for the anti-inflammatory activity attributed to IgG4 antibodies.