Contrast in adaptive mass gains: Eurasian golden plovers store fat before midwinter and protein before prebreeding flight

Before predictable periods of high nutritional demand and little or no intake, vertebrates store fuel mainly composed of energy-dense lipids or energy-poor but protein-rich muscle tissue. Documenting contrasts in fuel composition and storage patterns within species, or even within individuals, would greatly help to elucidate the functional significance of the variety of storage strategies demonstrated in birds. We show here that the 40-50 g mass gain of 200 g in Eurasian golden plovers (Pluvialis apricaria) in autumn in The Netherlands consists of fat only, but that the similar gain in body mass in spring consists of proteinaceous tissue (pectoral and other skeletal muscle and possibly skin tissue). That the same golden plovers store energy in autumn and store protein in spring suggests that they face energy deficits in early winter and risk protein deficits in spring, especially perhaps after arrival on the breeding grounds in late April and early May. In autumn and winter their diet consists largely of protein-rich earthworms, but upon arrival on Low Arctic and montane tundras, golden plovers tend to eat berries which are rich in sugars but notably poor in proteins. We therefore propose that the build-up of proteinaceous tissue in spring reflects a strategic storage of a nutritional resource that is likely to be in short supply somewhat later in the year.     

Susceptibility of the taro beetle, Papuana uninodis (Coleoptera, Scarabaeidae) to two new Bacillus popilliae isolates from Papuana spp

Two morphological types of Bacillus popilliae, causal agent of the milky disease, have been isolated from taro beetles (Papuana spp, Coleoptera: Scarabaeidae). B. popilliae from P. woodlarkiana woodlarkiana (Papua New Guinea) was a type A1 with a small sporangium (4.1 x 1.6 microm) and a large spore (2.1 x 1.4 microm) and parasporal body (1.8 x 1.2 microm) that sometimes overlap. B. popilliae from P. uninodis and P. woodlarkiana laevipennis (Solomon Islands) was a type B2 with a small sporangium (2.8 x 1.3 microm), a small eccentric spore (1.1 x 0.7 microm), and no parasporal body. The infectivity of these B. popilliae to Papuana uninodis larvae was compared with two B. popilliae samples from Popillia japonica in injection tests. The hemolymph of P. uninodis supported the germination and growth of isolates from Papuana and P. japonica. Results were similar in third instars and adults. Highest infection (spores present) and mortality was caused by the isolates from Papuana: mortality reached almost 100% 4 weeks after injection of the B2 type B. popilliae with 40% of larvae and 52% of adults infected. Injection of type A1 caused lower mortality but a similar percentage infected. Of two A1 B. popilliae from P. japonica, one caused a mortality comparable to type A1 from Papuana but lower infection; an older isolate resulted in low mortality and only one infected larva. B. popilliae type A1 from P. woodlarkiana was produced in the Solomon Islands by injection of spores in P. uninodis. Thirty four percent of the injected larvae and 31% of the adults produced spores with an average yield of 3.2 and 0.8 x 10(9) spores/insect, respectively. Oral application of a single dose of 10(7) spores of the B. popilliae isolates from P. uninodis or P. japonica did not cause infection and similarly inoculation of the food with spores of B. popilliae type B2 did not result in infections. However, when different rates were applied to the food of second- and third-instar P. uninodis, the B. popilliae type A1 from P. woodlarkiana caused up to 15% infection and concentration-related mortality.     

Freeze-fracture studies on isolated sperm cells ofSpinacia oleracea L.

Summary With freeze-fracturing sperm cells appear to be fractured preferentially through the plasma membranes. Only few fracture planes through the cytoplasm are found. Both the PF as well as the EF side of the sperm cell plasma membranes show a slightly undulating surface and contain intramembrane particles. The particle distribution is irregular and does not show any clustering. The EF side of the plasmamembrane contains approximately 3 times more particles per m² than the PF side.Abbreviations EF extraplasmatic fracture face - IMP intramembrane particles - FDA fluorescein diacetate - PF plasmatic fracture face     

Studies of the Mature Pollen of Spinacia oleracea after Freeze Substitution and Observed with Confocal Laser Scanning Fluorescence Microscopy

The three-dimensional configuration of the nuclei of the trinucleate pollen grain of Spinacia oleracea L. has been examined by means of confocal laser scanning fluorescence microscopy (CLSM). It shows the presence of a male germ unit (MGU) in which all three nuclei are usually positioned in the periphery of the pollen grain. After freeze fixation and freeze substitution, the ultrastructure is better preserved than with standard chemical fixation. It shows the presence inside the pollen grain of mitochondria, dictyosomes, large starch-containing plastids, endoplasmic reticulum (ER), vacuoles and the MGU. In the sperm cells mitochondria, vesicles, dictyosomes and ER are also found. No microtubules were found in the grain and only very few inside the sperm cells. This is in contrast with earlier published results where fluorescent-labeled antibodies were used.     

Determination of saponins in Maesa lanceolata by LC-UV: development and validation

Triterpene saponins are a class of plant natural products with a wide range of bioactivities, which makes them an interesting research subject. The small tree Maesa lanceolata, growing in African countries, is used in traditional medicine against various diseases. In previous work a triterpenoid saponin mixture was isolated from the leaves of M. lanceolata and the compounds were identified as closely related oleanane type triterpenes [Apers, S., Foriers, A., Sindambiwe, J.B., Vlietinck, A., Pieters, L., 1998. Separation of a triterpenoid saponin mixture from Maesa lanceolata: semi preparative reversed-phase wide pore high performance liquid chromatography with temperature control. J. Pharm. Biomed. Anal. 18, 737; Apers, S., De Bruyne, T.E., Claeys, M., Vlietinck, A.J., Pieters, L.A.C., 1999. New acylated triterpenoid saponins from Maesa lanceolata. Phytochemistry 52, 1121]. The compounds showed virucidal, haemolytic, molluscicidal and antiangiogenic activity [Apers, S., Baronikova, S., Sindambiwe, J.B., Witvrouw, M., De Clercq, E., Vanden Berghe, D., Van Marck, E., Vlietinck, A., Pieters, L., 2001. Antiviral, haemolytic and molluscicidal activities of triterpenoid saponins from Maesa lanceolata: establishment of structure-activity relationships. Planta Med. 67, 528; Apers, S., Bürgermeister, J., Baronikova, S., Vermeulen, P., Paper, D., Van Marck, E., Vlietinck, A.J., Pieters, L.A.C., 2002. Antiangiogenic activity of natural products: in vivo and in vitro test models. J. Pharm. Belg. 57 (Hors-série 1), 47]. Here we report the development of an extraction and quantification method to analyse saponin compounds in roots and leaves of M. lanceolata. After a purification step using C(18) solid phase extraction (SPE) cartridges, the samples were analysed on a LC-UV/MS system. The identification of the peaks from the different saponins was confirmed based on the retention time and mass spectrum. The quantification was performed using the UV signals. The standard oleanolic acid curve was linear over a concentration range of 2.8-140.0mug/mL. The recovery from the leaves was 94.5%. The precision of the method with respect to time and concentration was acceptable, with relative standard deviation (RSD%) values of 4.9 and 4.3, respectively.     

Body mass and latitude both correlate with primary moult duration in shorebirds

We investigated the effects of body mass and latitude on primary moult duration from published data of migrating shorebirds that moult exclusively on the wintering grounds. Non‐phylogenetic and phylogenetic models demonstrated that body mass and latitude correlate with moult duration in a non‐additive way: the models predict different latitudinal relationships for smaller and larger shorebirds, and in the northern hemisphere, primary moult duration increased allometrically with body mass (exponent = 0.17), whereas in the southern hemisphere, primary moult duration was not correlated with body mass. If birds optimize feather quality and if slower moult yields sturdier feathers, the fast primary moult of northerly wintering shorebirds indicates additional selection pressures at work.     

Management of modern agricultural landscapes increases nest predation rates in Black‐tailed Godwits Limosa limosa

Effective conservation of endangered species requires a solid understanding of the demographic causes of population change. Bird populations breeding on agricultural grasslands have declined because their preferred habitat of herb‐rich meadows has been replaced by grassland monocultures. The timing of agricultural activities in these monocultural grasslands is critical, as they often coincide with the nesting phase of breeding birds. Here, we aim to identify the effect of habitat management and targeted nest protection on nest survival of Black‐tailed Godwits Limosa limosa in the Netherlands, a population that has shown a 70% reduction in breeding population size since the 1970s. To protect nests in monocultures from destruction, farmers are paid to either delay mowing or leave a patch of unmown grass around the nest, a patch which in practice varied in size. In herb‐rich meadows, which are typically managed for bird conservation purposes, mowing occurs after hatching. Nest survival declined as the season advanced, more steeply on monocultures than on meadows. Targeted nest protection was only partially successful, as nest predation was considerably higher on mown grassland monocultures with small unmown patches around the nest than in mown monocultures with large unmown patches and in unmown fields. Increased predator densities over the years have been suggested as an important cause of the trend towards lower nest survival, but here we show that nest survival was higher on herb‐rich meadows than on monocultures, and similar to the 1980s. It thus seems that increased predator densities are an increased threat during the egg stage only if habitat quality is low. High‐quality habitat in the form of herb‐rich meadows therefore provides a degree of protection against predators.     

Morphological and digestive adjustments buffer performance: How staging shorebirds cope with severe food declines

Organisms cope with environmental stressors by behavioral, morphological, and physiological adjustments. Documentation of such adjustments in the wild provides information on the response space in nature and the extent to which behavioral and bodily adjustments lead to appropriate performance effects. Here we studied the morphological and digestive adjustments in a staging population of migrating Great Knots Calidris tenuirostris in response to stark declines in food abundance and quality at the Yalu Jiang estuarine wetland (northern Yellow Sea, China). At Yalu Jiang, from 2011 to 2017 the densities of intertidal mollusks, the food of Great Knots, declined 15‐fold. The staple prey of Great Knots shifted from the relatively soft‐shelled bivalve Potamocorbula laevis in 2011–2012 to harder‐shelled mollusks such as the gastropod Umbonium thomasi in 2016–2017. The crushing of the mollusks in the gizzard would require a threefold to 11‐fold increase in break force. This was partially resolved by a 15% increase in gizzard mass which would yield a 32% increase in shell processing capacity. The consumption of harder‐shelled mollusks was also accompanied by reliance on regurgitates to excrete unbreakable parts of prey, rather than the usual intestinal voidance of shell fragments as feces. Despite the changes in digestive morphology and strategy, there was still an 85% reduction in intake rate in 2016–2017 compared with 2011–2012. With these morphological and digestive adjustments, the Great Knots remaining faithful to the staging site to a certain extent buffered the disadvantageous effects of dramatic food declines. However, compensation was not complete. Locally, birds will have had to extend foraging time and use a greater daily foraging range. This study offers a perspective on how individual animals may mitigate the effects of environmental change by morphological and digestive strategies and the limits to the response space of long‐distance migrating shorebirds in the wild.