The in vitro banana-leaf-fragment technique preserves the photosynthetic apparatus

In vitro studies of plant-pathogen interactions using leaf-fragments remains controversial compared to those studies under field conditions. The leaf-fragments technique, which predominantly uses benzimidazole in the culture medium to retard senescence, has been reported as reliable, fast, and inexpensive for analysis of aggressiveness and resistance in the Mycosphaerella fijiensis-Musa spp. interaction. However, no data have been published verifying whether in vitro banana leaf fragments maintain photosynthetic activity, which is a requirement for studying this interaction. In this study, maximum quantum efficiency of photosystem II, electron transport rate, transpiration, carbon dioxide exchange, light saturation point, and stomatal density were evaluated in in vitro leaf fragments of the Grand Nain banana genotype. Furthermore, the same parameters were also attained for leaves from plants in the field (during two seasons) and greenhouse conditions. The photosynthetic yield was constant during the experiment in leaf fragments with benzimidazole, and the photosynthetic rates on day 30 were similar throughout the whole experiment. This study supports that the banana-leaf-fragment technique as such protects the photosynthetic apparatus and then is suitable for studies on interactions such as that of M. fijiensis-Musa acuminata.

Compound-Specific Radiocarbon Analysis of Organic Compounds from Mount Fuji Proximal Lake (Lake Kawaguchi) Sediment, Central Japan

ABSTRACTDifferential sources of sedimentary organic compounds in a volcanic region were revealed by determining radiocarbon content (Δ14C) of organic compounds in surface sediments from Lake Kawaguchi, at the northern foot of Mount Fuji, central Japan. The Δ14C values of C16 fatty acid (−124‰) and chlorophyll a (Chl a) (−133‰) were similar to the Δ14C of dissolved inorganic carbon (DIC) in surface water (−117‰), suggesting that a significant portion of these compounds originated from modern primary producers with a reservoir age of ~1000 years. On the other hand, a large offset between the Δ14C values of Chl a (−133‰) and those of 132, 173-cyclopheophorbide-a-enol (−169‰) and pheophytin a (−179‰) suggested contributions from older pigments. In addition, the Δ14C of long-chain (C24, C26, and C28) fatty acids (−183 to −75‰) showed a large offset from that of a plant leaf remain (0‰) within sediments, demonstrating that the long-chain fatty acids were affected by substantial contributions from pre-aged terrestrial materials. Overall, the sedimentary organic compounds gave 14C ages older than the plant leaf fragment within sediments; however, the similarity between Δ14C of the C16 fatty acid and DIC implies potential for applying compound-specific radiocarbon analysis as a dating tool in volcanic lake environments.

Two castes sizes of leafcutter ants in task partitioning in foraging activity

ABSTRACT: Task partitioning in eusocial animals is most likely an evolutionary adaptation that optimizes the efficiency of the colony to grow and reproduce. It was investigated indirect task partitioning in two castes sizes; this involves task partitioning in which the material transported is not transferred directly from one individual to another, but where it is dropped by one ant to be picked up by another. In two separate approaches, it was confirmed previous results pertaining to leaf caching activities among Atta colombica with task partitioning activities involving leaf dropping among Atta sexdens rubropilosa , in which there is a correlation between the size of an individual ant and the leaf fragment it transports. It was also suggested that this correlation exists only in individual ants that cut and transport (CaT) the same fragment to the nest. When task partitioning occurs and individual ants transporting (T) leaf fragments cut by other ants, the correlation becomes looser or disappears. We also observed that CaT ants are smaller than T ants.

Faecal particle size and tooth wear of the koala (Phascolarctos cinereus)

We used computer-aided image analysis of leaf fragment particles found in faecal pellets of 45 koalas, representing the range of tooth wear in this species, to investigate how tooth wear in the koala influences faecal particle sizes. Although the range of sizes of particles produced did not vary between koalas across different tooth wear classes, with all koalas producing small, medium and large particles, koalas with advanced tooth wear produced a greater proportion of larger particles. This observation may prove useful for demographic population analyses based on scat surveys since the broad age class of individual koalas can be estimated from faecal pellet analysis. Older koalas produced faecal pellets containing a higher proportion of the largest-sized particle sizes (those greater than 0.59 mm2) than either young or mature koalas but there was no difference detected between mature and young koalas.

Optimality in a partitioned task performed by social insects

Biologists have long been aware that adaptations should not be analysed in isolation from the function of the whole organism. Here, we address the equivalent issue at the scale of a social insect colony: the optimality of component behaviours in a partitioned sequence of tasks. In colonies of Atta colombica , a leaf-cutting ant, harvested leaf tissue is passed from foragers to nest workers that distribute, clean, shred and implant the tissue in fungal gardens. In four laboratory colonies of A. colombica , we found that the highest colony-wide rate of leaf tissue processing in the nest was achieved when leaf fragment sizes were suboptimal for individual delivery rate by foragers. Leaf-cutting ant colonies appear to compromise the efficiency of collecting leaf tissue in order to increase their ability to handle the material when it arrives in the nest. Such compromise reinforces the idea that behavioural adaptations, like adaptations in general, must be considered within the context of the larger entity of which they are a part.

Re-Dating Mid-Holocene Betelnut (Areca Catechu L.) and Other Plant Use at Dongan, Papua New Guinea

Direct accelerator mass spectrometry (AMS) dating of anaerobically preserved plant remains from the Dongan site in New Guinea, combined with assessment of preservation condition, confirms earlier doubts about the antiquity of betelnut (Areca catechu L.) found at the site. A possible sago leaf fragment is also identified as a modern contaminant. The mid-Holocene age of other fruit and nut remains is verified using these methods. The utility of AMS dating in combination with detailed archaeobotanical assessment is demonstrated, thus improving chronometric hygiene and with it knowledge of past plant use in Oceania.

Programinis burmitis gen. et sp. nov., and P. laminatus sp. nov., Early Cretaceous grass-like monocots in Burmese amber

The remains of a spikelet and a leaf of an Early Cretaceous grass-like monocot in Burmese amber are described as Programinis burmitis gen. et sp. nov., and P.�laminatus sp. nov., respectively. The laterally compressed spikelet of P.�burmitis has two basal sterile glumes, a series of lemmas and paleas and remains of stamens and a gynoecium. Adjacent to the spikelet are spherical, monoporate pollen grains. The epidermis of the leaf fragment of P.�laminatus contains numerous stomata with well-defined, sausage-shaped guard cells with elongate nuclei, rows of epidermal cells with long and short cells and spherical and elliptical silica-like bodies in cuboid epidermal cells. Unpointed papillae and uniseriate bicellular microhairs, both raised, occur on the leaf surface. Programinis burmitis and P.�laminatus are considered early bambusoid types that grew in tropical, forested habitats. Their discovery suggests that true grasses may have evolved in South-east Asia, since the Burmese amber mines are located on the Burma Plate, part of Laurasia.

A London Pewterer's Workshop in 1551

A three-leaf fragment of an unidentified London pewterer's business records, covering some three months of the year 1551, has been found among the archives of the Worshipful Company of Pewterers and is here transcribed together with a discussion of its contents. It provides an inventory of the pewterer's stock, describes the alloying and casting of over a ton of tin to produce a wide range of pewter flatware, and itemizes the sales and loans of pewterware to named customers. These include other pewterers and Alderman Richard Lambert. The manuscript provides a unique insight into a sixteenth century pewterer's workshop practices. Speculation into the identity of the pewterer has proved inconclusive.