Starch is a major part of our diet. Food processing determines the physicochemical properties of starch in processed foods. An understanding of such properties is important in the development of strategies to modulate desirable textural attributes as well as the digestibility of starch in foods such as baked and extruded products. This review summarises the molecular interactions that occur during gelatinization and retrogradation of starch molecules studied using starch‐water systems focusing on those with starch concentrations of 60–150% db relevant to baked and extruded foods. Little information exists on effects of starch concentration on digestibility and polymer conformations and structures of processed starch in concentrated systems. 相似文献
Tannins occur in many plant species, and they often suppress intake by reducing nutrient availability or by causing malaise. Polyethylene glycol (PEG) binds to tannins and may thereby increase the availability of macronutrients and decrease malaise. Supplemental PEG increases intake of tannin-containing plants by sheep, goats, and cattle. Given the strong response to supplemental PEG, we speculated that animals might self-regulate their intake of PEG when offered foods high in tannins. The objective of the first experiment was to determine if the amount of supplemental PEG (0, 25, 50, 75, or 100 g; molecular weight, 3,350) affected intake by lambs of a food (milo-tannin mix) containing 20% quebracho tannin. There was a linear relationship (Y = 272 + 1.2X; R2 = .86; P = .023) between the amount of supplemental PEG ingested and the subsequent intake of milo-tannin food by lambs. The objective of the second experiment was to determine whether lambs self-regulated intake of PEG when fed a ration that contained 0, 5, 10, 15, or 20% quebracho tannin and whether they adjusted their intake of PEG when tannin was removed from the diet. There was a positive relationship between the amount of PEG ingested and intake of food and tannin (P = .0001). Lambs fed high-tannin diets ate more PEG than controls (P = .03). Lambs fed the 20% tannin diet ate the most PEG, and controls ate the least PEG. Tannin limited intake of the diets, but PEG attenuated the response to a great degree (P = .065). Immediately after tannin was removed from the ration, lambs that formerly had been fed the 20% tannin ration ate more PEG than lambs fed the other rations (P = .0075). Ten of the lambs (5 from the 20% tannin group, 1 from the 15% tannin, and 2 each from the 10 and 5% groups) continued to eat PEG for 7 d after tannin was removed from their ration. When they were tested again 6 wk after the trial and offered tannin-free diets, their intake of PEG had decreased. 相似文献
Worldwide, anthropogenic habitat loss and degradation have led to substantial biodiversity declines. Preserving biodiversity requires an understanding of how habitat loss and degradation interact to impact species populations, and how land-use decisions can limit these losses.
Objectives
We present a mathematical partitioning of changes in landscape-level population abundance in response to land-use change using a modified version of the Price equation from evolutionary biology.
Methods
The Price equation partitions changes in species abundance into multiple drivers related to habitat loss, habitat degradation, and their interaction. We describe its development and exemplify its applicability using simulated data.
Results
Applying the Price equation to simulated data reveals the roles of habitat loss, habitat degradation, and their interaction in driving population change in patchy landscapes undergoing complex land-use change processes.
Conclusions
The Price equation is a theoretical tool that may enhance our understanding of the effects of land-use change on populations by accounting for the specific processes by which land-use change operates across landscapes.
The transition from hunting gathering to a farming based economy – the Neolithic Revolution, was a crucial junction in the
human career, attracting the attention of many scholars: archaeologists, anthropologists, geographers, botanists, geneticists
and evolutionists among others. Our understanding of this major transformation is rather limited mainly due to the inability
to fully reconstruct the cultural, biological and environmental setup of the relevant period and organisms involved. Many
students of the subject of plant domestication have seriously entertained the hypothesis that man's first crop plants have
originated from weeds associated with the disturbed habitats surrounding pre-agricultural ancient human dwellings and or with
human refuse heaps – the so called ‘dump heap hypothesis’. In this paper we re-examine this hypothesis in light of the known
biology of the Near Eastern founder crops and the ecological preferences of their wild progenitors. Contrary to the ‘dump-heap
hypothesis’, we propose that Near Eastern farming originated as a result of a long term interaction between humans and plants
and was mainly driven by the nutritional features of the respective crops and cultural forces. 相似文献
Background Increasing awareness in the last decade concerning environmental quality had prompted research into ‘green solutions’ for
soil and water remediation, progressing from laboratoryin vitro experiments to pot and field trials.
In vitro cell culture experiments provide a convenient system to study basic biological processes, by which biochemical pathways,
enzymatic activity and metabolites can be specifically studied. However, it is difficult to relate cell cultures, calli or
even hydroponic experiments to the whole plant response to pollutant stress. In the field, plants are exposed to additional
a-biotic and biotic factors, which complicate further plant response. Hence, we often see thatin vitro selected species perform poorly under soil and field conditions. Soil physical and chemical properties, plantmycorrhizal
association and soil-microbial activity affect the process of contaminant degradation by plants and/or microorganisms, pointing
to the importance of pot and field experiments.
Objective This paper is a joint effort of a group of scientists in COST action 837. It represents experimental work and an overview
on plant response to environmental stress fromin vitro tissue culture to whole plant experiments in soil.
Results Results obtained fromin vitro plant tissue cultures and whole plant hydroponic experiments indicate the phytoremediation potential of different plant species
and the biochemical mechanisms involved in plant tolerance. In pot experiments, several selected desert plant species, which
accumulated heavy metal in hydroponic systems, succeeded in accumulating the heavy metal in soil conditions as well.
Conclusions and Recommendations
In vitro plant tissue cultures provide a useful experimental system for the study of the mechanisms involved in the detoxification
of organic and heavy metal pollutants. However, whole plant experimental systems, as well as hydroponics followed by pot and
field trials, are essential when determining plant potential to remediate polluted sites. Multidisciplinary research teams
can therefore increase our knowledge and promote a practical application of phytoremediation. 相似文献
A priority list of 323 plant species was created through a consultative process for ex situ conservation in the recently inaugurated Israel Plant Gene Bank (IGB). The IGB is set up to preserve plant genetic resources and the endangered genetic variability of the Israeli flora. Upon its inauguration, we consulted with the country’s leading plant breeders and botanists in an attempt to create a list of the most important plant species to be included in the initial collections. The list includes crop wild relatives (CWRs), selected according to their contribution to humans: edible plants (grains, vegetables, oil); forage plants; species with potential industrial and biotechnological applications (e.g. spices, medicinal plants, aromatic plants, fibers, dyes), and species with horticultural and forestry potential. We further ranked the species on the basis of assessed values for each of seven characteristics: distribution range in the country; abundance; rarity of the growing habitats; endemism; red number index—representing imminent threat of extinction; availability of samples in Israeli collections, and genetic relationship to cultivated crops. The sum of the assessed values for these seven characteristics was used to group the species on the list into four main prioritized-collection schemes. Statistical analysis indicated that all attributes had similar influence on the collecting prioritization scheme. In general, rare species with low abundance in their growing habitats were ranked in the highest priority group, while highly distributed species were sorted together into a lower priority group. The prioritization scheme will be used to optimize the collection in the IGB with the aim of establishing its collecting activities. 相似文献
The nematode Spirocerca lupi is primarily a parasite of dogs, which causes typical lesions of esophageal nodular granulomas, aortic aneurysms and spondylitis. In order to evaluate the therapeutic effect of doramectin on experimental canine spirocercosis, seven beagle dogs experimentally infected with 40 infectious S. lupi larvae (L(3)) were treated with doramectin. Treatment was commenced following endoscopic visualization of esophageal granulomas, and typical S. lupi eggs were detected in the feces. The treatment protocol included six treatments of doramectin (400 microg/kg subcutaneously) at 2 weeks intervals, followed by monthly injections until the disappearance of the esophageal granulomas or the end of the study (768 days post-inoculation).Eggs could not be found on fecal examinations 3-10 days after the first or second doramectin treatment. In addition, a gradual decrease in size of granulomas was noticed in all seven dogs during the course of the study. Esophageal granulomas had completely resolved in six of the seven dogs between day 35 and day 544 post-initial doramectin treatment, by day 35 in one dog (after three treatments), by day 43 in two dogs (after four treatments), by day 98 in one dog (after seven treatments), by day 460 in one dog (after 18 treatments) and by day 544 in another dog (after 21 treatments). In one dog, remnants of S. lupi granulomas could still be seen 544 days post-initiation of treatment with doramectin. Multiple subcutaneous injections of doramectin (400 microg/kg) were shown to be effective and safe in the treatment of canine spirocercosis. 相似文献