A presumed spelaeogriphacean crustacean from an upper Barremian wetland (Las Hoyas; Lower Cretaceous; Central Spain)

Abstract: A third fossil attributable to the crustacean peracarid order Spelaeogriphacea is described from an Upper Barremian (125 Ma) lacustrine environment in Central Spain. Neither the new taxon, Spinogriphus ibericus gen. et sp. nov., nor the two already described fossil forms can be identified with certainty as crown‐group spelaeogriphaceans. We consider that Schram’s 1974 family Acadiocarididae represents stem‐lineage spelaeogriphaceans and should accommodate these fossil taxa that display very generalised peracaridan features and lack any conspicuous autapomorphies, except for a short carapace, undifferentiated pereiopods, foliaceous pleopods and a tail fan‐like (uropods + telson) caudal structure where the unsegmented uropodal endopod lacks annulation. The zoogeography of the Acadiocarididae is Laurasian in contrast to the modern, crown‐group spelaeogriphaceans (Spelaeogriphidae), which are limited to Gondwanan territories.     

The Growth Activity and Fertilizing Capacity of Submersely Cultivated Pollen Tubes of Nicotiana tabacum L.

Tobacco pollen was cultivated in shaken suspension culturesand the growth estimated by weighing the mass of germinatedpollen separated from the nutrient solution. A formula for calculatingmean pollen tube length from the weight of the culture has beenderived for this pollen species. The growth of pollen tubes in vitro is shown to have a rhythmiccharacter. The rapid growth comparable to the mean growth ratein styles is limited to short time intervals alternating withprogressively extending periods of very depressed growth, whichceased entirely after 10–12 h of cultivation. When tested by placental pollination in vitro, the fertilizingcapacity of the pollen culture was found to increase duringthe first hour of cultivation but to decrease steadily thereafter.On the other hand, with the application of pollen tubes fromculture on stigma, a short precultivation period and even themere wetting of pollen had a negative effect on the seed set.With pollen cultivated longer than 4 h, no seed formation wasobserved.     

Re‐contemplate an entangled bank: The Power of Movement in Plants revisited

We review the ways in which two of Charles Darwin's lesser known works, The Movement and Habit of Twining Plants and The Power of Movement in Plants, stimulated 20th and 21st century research findings and philosophies. The legacy of Darwin's work permeates research on plant movement. For example, Darwin's demonstration that coleoptiles and roots fail to bend in response to light or gravity if their tips are removed helped researchers work toward the discovery of auxin and other plant hormones. Darwin's methodical observations on vine twining directions and circumnutation foreshadowed the recent discovery that 92% of vines twine in right‐handed helices, regardless of their location on the planet. Finally, Darwin's observation of the similarity between plant responses to stimuli and the responses of lower animals foreshadowed the current debate over whether plants have ‘behaviour’. Thus, even Darwin's lesser‐known works continue to influence research in the present day. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 111–118.     

Patterns of seasonal and yearly mass variation in West African tropical savannah birds

Birds in the northern hemisphere usually increase mass reserves in response to seasonal low temperatures and shorter day length that increase foraging unpredictability and so starvation risk. In the lowland tropics, relatively low temperatures and short day lengths are absent and so the risk of starvation may be reduced, leading to much smaller seasonal effects on mass. Nevertheless, other factors such as high temperatures and water and food availability may vary greatly between tropical wet and dry seasons, leading to variable starvation risk and seasonal mass effects. Using data collected from 47 species of birds caught over a 10‐year period in a tropical savannah region in West Africa we tested for seasonal variation in mass in response to a predictable, strongly seasonal tropical climate. Many species (91%) showed seasonal variation in mass, and this was often in a clear annual pattern that was constant across the years. Many species (89%) varied their mass in response to seasonally predictable rainfall. Annual variation in mass was also important (45% of species). Relatively few species (13%) had a seasonal pattern of mass variation that varied between years. Feeding guild or migratory status was not found to affect seasonal or annual mass variation. Seasonal mass change was on average 8.1% across the 21 species with a very large sample size and was comparable with both northern and southern temperate species. Our study showed that biologically significant consistent seasonal mass variation is common in tropical savannah bird species, and this is most likely in response to changing resource availability brought about by seasonal rainfall and the interrupted foraging response due to the constraints of breeding.     

Photodecomposition of Monogalactosyl Diglyceride Mediated by Chlorophyll

In acetone extracts the presence of chlorophyll a and b caused enhanced photodecomposition of monogalactosyl diglyceride. Irradiation of isolated etioplasts containing chlorophyllide and monogalactosyl diglyceride caused photodecomposition of chlorophyllide but not of monogalactosyl diglyceride. In irradiated etiochloroplasts containing chlorophyll a and monogalactosyl diglyceride both components were photodecomposed. During photodecomposition of monogalactosyl diglyceride the fatty acid composition remained constant.     

The Mechanism of Evagination of Imaginal Discs of Drosophila melanogaster

The evagination of imaginal leg discs to produce legs is a usefulmodel for studying morphogenesis. Evagination of imaginal legdiscs occurs in vitro in defined culture media in the presenceof the molting hormone ß-ecdysone. Evagination involveslimited, organized movement of imaginal disc cells. The movementappears to be a result of contractile activity, coordinatedwith the presence of appropriate structural and surface propertiesof disc cells. However, ecdysone does not produce its effectsdirectly, but acts through the genome to cause evagination.Evagination is a result then of increased synthesis of differentproteins, one of which is myosin. If the results on discs aregeneralizable they indicate that similar morphogenetic processesare the direct result of the readout of the specific geneticprograms.     

Expressed sequence tags from the flower pathogen Claviceps purpurea

The ascomycete Claviceps purpurea (ergot) is a biotrophic flower pathogen of rye and other grasses. The deleterious toxic effects of infected rye seeds on humans and grazing animals have been known since the Middle Ages. To gain further insight into the molecular basis of this disease, we generated about 10 000 expressed sequence tags (ESTs)—about 25% originating from axenic fungal culture and about 75% from tissues collected 6–20 days after infection of rye spikes. The pattern of axenic vs. in planta gene expression was compared. About 200 putative plant genes were identified within the in planta library. A high percentage of these were predicted to function in plant defence against the ergot fungus and other pathogens, for example pathogenesis-related proteins. Potential fungal pathogenicity and virulence genes were found via comparison with the pathogen–host interaction database (PHI-base; http://www.phi-base.org ) and with genes known to be highly expressed in the haustoria of the bean rust fungus. Comparative analysis of Claviceps and two other fungal flower pathogens (necrotrophic Fusarium graminearum and biotrophic Ustilago maydis ) highlighted similarities and differences in their lifestyles, for example all three fungi have signalling components and cell wall-degrading enzymes in their arsenal. In summary, the analysis of axenic and in planta ESTs yielded a collection of candidate genes to be evaluated for functional roles in this plant–microbe interaction.