Tetrazolium salt as a seed germination indicator

A preliminary assessment of 2:3:5-triphenyl tetrazolium chloride as a seed germination indicator has been made by testing wheat, barley, oats, peas and vetches. Results as reliable as actual germination tests have been obtained, and the optimum conditions for testing have been determined. The application of this technique to other seeds is also discussed.     

Bilateral asymmetry in skeletal growth and maturation as an indicator of environmental stress.

This study examined the efficacy of bilateral asymmetry in epiphyseal union as an indicator of environmental stress affecting the skeleton. We compared the extent of asymmetry in the postcranial skeleton between two cemetery samples excavated from Medieval Kulubnarti, Sudanese Nubia. Past studies have strongly suggested that these ancient Nubians experienced environmental stress-the early Christian period (550-750 AD) population to a greater extent than the late Christian period (750-1450 AD) population. We hypothesized that if bilateral asymmetry is a reflection of stress, then it should be present or greater in the more stressed population, the early Christian period population, while absent or found to a lesser extent in the less stressed population, the late Christian period population. We computed two mean values, representative of right-side and left-side epiphyseal union, for each individual in both cemetery samples, and tested for significant differences. Bilateral asymmetry was significant in the combined cemetery sample of 90 individuals (P < 0.019). When cemetery samples were tested separately, bilateral asymmetry was significant for the early Christian period sample (P < 0.001), but not for the late Christian period sample. There were no differences attributable to sex. Finally, we discuss why we conclude that environmental stress was favored over a biomechanic explanation as the cause for asymmetry. To the extent that our results support previous findings that early Christian period individuals were more affected by environmental stress than late Christian period individuals, it is reasonable to consider bilateral asymmetry in skeletal growth and maturation a good indicator of environmental stress.     

Leaf developmental stability of Platanus acerifolia under urban environmental stress and its implication as an environmental indicator

The developmental stability indices,leaf width based fluctuating asymmetry (FA1),and lateral vein length based directional asymmetry (RDA1) of Platanus acerifolia were studied.All the leaves were sampled from 14 sites that were categorized based on different urban environmental stress levels (UESL) in Shanghai metropolitan,China.Besides,foliar stomatal density and stomatal length were also studied as the subsidiary indices to test the availability of developmental stability indices as the indicator under a stressful environment.Results showed seasonal variation of FA1 and RDA1 existed among the 14 sites,but the data showed significant negative correlation between FA1 and UESL (FA1=0.029-0.000 9UESL+0.000 3UESL2,r=0.766 5,P=0.001 4).However,a similar trend was not found between RDA1 and UESL.Furthermore,the significant correlation among FA1 and leaf stomatal length and stomatal density implied they could be used as indicators of urban stress levels on a small scale.It seemed that RDA1 was possibly a normal parameter during leaf development but it was unavailable for use as an indicator of urban stresses.     

Lacustrine profundal meiobenthos as an environmental indicator

Organic loading and eutrophy is indicated at profundal depths by large numbers of resting copepodid stages of cyclopoid copepods, by the occurrence of the naidid oligochaete species, Amphichaeta leydigii and Specaria josinae, and the harpacticoid species Canthocamptus staphylinus, and by a low meiobenthos/macrobenthos biomass ratio. An oligotrophic environment is indicated by the occurrence of the aeolosomatid oligochaetes Aeolosoma quaternarium, A. hemprichi and Rheomorpha neiswestnovae, the naidid oligochaete Chaetogaster langi and the harpacticoid species Attheyella crassa and a high meiobenthos/macrobenthos biomass ratio.     

Leaf developmental stability of Platanus acerifolia under urban environmental stress and its implication as an environmental indicator

The developmental stability indices, leaf width based fluctuating asymmetry (FA1), and lateral vein length based directional asymmetry (RDA1) of Platanus acerifolia were studied. All the leaves were sampled from 14 sites that were categorized based on different urban environmental stress levels (UESL) in Shanghai metropolitan, China. Besides, foliar stomatal density and stomatal length were also studied as the subsidiary indices to test the availability of developmental stability indices as the indicator under a stressful environment. Results showed seasonal variation of FA1 and RDA1 existed among the 14 sites, but the data showed significant negative correlation between FA1 and UESL (FA1 = 0.029 − 0.000 9UESL + 0.000 3UESL², r = 0.766 5, P = 0.001 4). However, a similar trend was not found between RDA1 and UESL. Furthermore, the significant correlation among FA1 and leaf stomatal length and stomatal density implied they could be used as indicators of urban stress levels on a small scale. It seemed that RDA1 was possibly a normal parameter during leaf development but it was unavailable for use as an indicator of urban stresses. __________ Translated from Chinese Journal of Ecology, 2005, 24(7): 719–723 [译自: 生态学杂志, 2005, 24(7): 719–723]     

Tetrazolium reduction in Saccharomyces cerevisiae

Summary The tetrazolium salt, 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) was used to determine viable respiring cells in batch cultures of Saccharomyces cerevisiae. Respiring cells reduce INT to water insoluble iodonitrotetrazolium formazan (INT-formazan) which is deposited within the respiring cell. The INT-formazan granules can be observed by brightfield microscopy. This allows a rapid quantitative determination of the percentage of respiring cells and total cells within the same microscopic field.In actively growing batch cultures of S. cerevisiae, the respiring cell count was equal to the total cell count for the first 72 h of the growth cycle. After 144 h of incubation only 22.7% of the total cell numbers were actively respiring.     

Pollen from surface samples as an environmental indicator

Palynological analysis of surface samples was accomplished within the framework of integrated ecological investigation of northwestern Timan-Pechora oil-and-gas-bearing province (sampling depth, 0.015 m). Palynological results corroborated geochemical conclusions and allow the author to suggest that this area is gametopathogenically hazardous. This hypothesis is supported by the peculiarities of teratomorphic pollen grains found in the surface samples.     

Diversity of Cenozoic marsupiate echinoids as an environmental indicator

McNamara, K.J. 1994 10 15: Diversity of Cenozoic marsupiate echinoids as an environmental indicator. Marsupiate echinoids are today largely confined to the seas around Antarctica. Consequently, it has often been inferred that the presence of marsupiate echinoids in the fossil record is indicative of the former existence of low oceanic temperatures. In this study the distribution of marsupiate echinoids through the Cenozoic succession of southern Australia is compared with palaeo-temperature data to test this assumption. The analysis reveals that there is no positive correlation between high marsupiate echinoid diversity during the Cenozoic and low oceanic temperatures. An alternative hypothesis, based on life-history strategies, is investigated. This reveals that marsupiate echinoids show many characteristics typical of organisms with slow growth, long life spans and production of few, large offspring. It is suggested that the northward migration of Australia during the Cenozoic from an original high-latitude location in the early Cenozoic was accompanied by an increase in environmental instability in the southern Australian region in the late Cenozoic. This led to a consequent decrease in marsupiate echinoid diversity. During the Pliocene these direct brooding echinoids were replaced by non-brooders with pelagic lecithotrophic larvae, which dominate the southern coastal echinoid fauna of Australia today. The environmental stability experienced in southern Australia in the early Cenozoic persisted throughout the Cenozoic in the Antarctic region, particularly with regard to predictability of nutrient supply. The result has been the dominance of marsupiate echinoids in that region today. Temporal changes in the diversity of marsupiate echinoids in southern Australia therefore supports the view that their spatial and temporal distribution may be more closely correlated with aspects of their life-history strategy and environmental stability than with low temperature. Echinoidea, evolution, diversity, life-history strategy, Cenozoic.     

Specific root length as an indicator of environmental change

Abstract

Specific root length (SRL, m g^?1) is probably the most frequently measured morphological parameter of fine roots. It is believed to characterize economic aspects of the root system and to be indicative of environmental changes. The main objectives of this paper were to review and summarize the published SRL data for different tree species throughout Europe and to assess SRL under varying environmental conditions. Meta-analysis was used to summarize the response of SRL to the following manipulated environmental conditions: fertilization, irrigation, elevated temperature, elevated CO₂, Al-stress, reduced light, heavy metal stress and physical disturbance of soil. SRL was found to be strongly dependent on the fine root classes, i.e. on the ectomycorrhizal short roots (ECM), and on the roots <0.5 mm, <1 mm, <2 mm and 1 – 2 mm in diameter SRL was largest for ECM and decreased with increasing diameter. Changes in soil factors influenced most strongly the SRL of ECM and roots <0.5 mm. The variation in the SRL components, root diameter and root tissue density, and their impact on the SRL value were computed. Meta-analyses showed that SRL decreased significantly under fertilization and Al-stress; it responded negatively to reduced light, elevated temperature and CO_2. We suggest that SRL can be used successfully as an indicator of nutrient availability to trees in experimental conditions.     

Triphenyltetrazolium chloride as an indicator of fine-root vitality and environmental stress in coniferous forest stands: Applications and limitations

The present study is an attempt to investigate whether triphenyltetrazolium chloride (TTC), a chemical compound which measures dehydrogenase activity, could be used to study fine-root vitality from two different points of view: (i) in relation to ageing; (ii) as an indicator of environmental stress, in this case of excess nitrogen. The study was performed with excavated fine-roots from middle-aged Norway spruce and Scots pine stands.The ageing aspect was investigated by applying TTC to fine roots separated into different vitality classes, based on certain morphological characteristics. A significant difference in activity was demonstrated only in the case of roots that could be referred to as living and dead, respectively. The use of TTC on fine roots grown at different nitrogen supply levels indicates a possible increase in dehydrogenase activity with increasing nitrogen supply.     

Corticolous lichens as environmental indicators in urban areas in southern Brazil

Lichens are considered bioindicators and, as such, are widely used for air quality monitoring, especially in urban-industrial areas. The present paper proposes an evaluation of lichen communities in urban areas. The corticolous lichen community was assessed at 29 sampling stations in the city of Porto Alegre, in addition to a reference area located in the State Park in the city of Viamão, southern Brazil. The rubber band method was used for lichen mapping; three hundred host-trees were analyzed, at 11 different height levels. Lichens were evaluated in terms of composition, richness, cover and diversity, and sampling stations were classified based on the Index of Atmospheric Purity (IAP) complemented by the Environmental Classification Factor (ECF). The inclusion of ECF as a complement to the original IAP formula is proposed in the present study and not only richness and cover components are considered, but also data on the lichenized mycota composition (considering its different morphological forms). One hundred and thirty-one (131) taxa have been identified, out of which 13 specimens may be considered as indicators of urban areas, and the predominance of taxa belonging to the crustose and foliose morphological group was verified. The sampling stations were classified into five zones, ranging from lichen-free zones to optimal zones for lichen development. The use of lichen proved to be efficient to both evaluate air quality and identify alterations of urban microclimates. The application of an ECF-based correction factor is expected to complement the use of IAP, making it a more sensitive index, since an analysis of a multivaried information profile was deemed necessary, especially in regions where specimen diversity is higher.     

Tetrazolium reduction and nitrogenase activity in heterocystous blue-green algae

Summary Heterocysts reduce triphenyl tetrazolium chloride (TTC) faster than vegetative cells apparently because the absence of the O₂-evolving photosystem II and the high electron transport activity in these cells. Although the rate of TTC reduction in vegetative cells is increased by the continuous removal of O₂ evolved in photosynthesis, it has not been possible to obtain rates of TTC reduction comparable with those in heterocysts probably because of the continued competition for electrons between TTC and O₂. The use of nitro-blue tetrazolium chloride (NBT) as a redox indicator has revealed the presence in filaments under aerobic conditions of a gradient of electron transport activity with strongest reducing power in the heterocysts, proheterocysts and vegetative cells next to heterocysts, and with gradually diminishing activity midway between two heterocysts. This pattern is indistinct in filaments grown under micro-aerophilic conditions. The strong electron transport activity in vegetative cells adjacent to heterocysts appears to promote reducing conditions in the heterocysts. Both, red-formazan formation in the heterocysts and blue-formazan deposition in vegetative cells greatly inhibit nitrogenase activity, and this was adversely affected also by the detachment of heterocysts from vegetative cells. The findings are consistent with the idea that the association of heterocysts with vegetative cells in essential for nitrogen fixation to occur in heterocystous blue-green algae.     

Wing shape versus asymmetry as an indicator of changing environmental conditions in insects

Abstract In insects, the fluctuating asymmetry of bilaterally symmetrical traits has been suggested as an indicator of environmental stress because asymmetry is expected to increase when stressful conditions disturb the normal development of organisms. However, the extensive literature on asymmetry–stress associations is indeterminate. Here we contrast changes in asymmetry with changes in an alternate stress indicator, the shape of insect wings. The development of wing shape involves numerous genes that act throughout egg-to-adult development, so stresses that act at a specific time could alter shape in specific ways. Shape changes, as measured by the Procrustes technique, were considered in five data sets: exposure of Drosophila melanogaster (Meigen) to multiple stresses involving ethanol, low nutrition and cold shocks; exposure of a chironomid ( Chironomus tepperi (Skuse)), a blowfly ( Lucilia cuprina (Wiedemann)), and lightbrown apple moth ( Epiphyas postvittana (Walker)) to pesticides; and development of C. tepperi under saline conditions. All these conditions influenced viability and development time. In none of these cases was a change in symmetry of wing size or wing shape detected. In contrast, in four of the five data sets there was a change in wing shape. These results suggest that wing shape may be altered more commonly by stress than trait asymmetry. Wing-shape monitoring may be useful in detecting stressful environmental conditions during development, at least under controlled conditions.     

Phytoplankton alpha diversity as an indicator of environmental changes in a neotropical floodplain

Habitat fragmentation, overexploitation of natural resources, the introduction of alien species and environmental degradation in aquatic environments are the main causes of reductions in aquatic biota diversity. Phytoplankton represent good ecological indicators because they are highly diverse and rapidly respond to a wide array of environmental disturbances. We investigated the interannual variation in alpha diversity of the phytoplankton community in lakes of an alluvial floodplain. We predicted that the phytoplankton diversity decreases over time in lakes and rivers subjected to human activities, whereas those biotopes in areas under pristine environmental conditions do not show a reduction in alpha diversity. Phytoplankton samples were taken quarterly over a period of eleven years (2000–2010), from ten localities associated with three large rivers, which showed different uses of the watershed. The time series of alpha diversity was analysed, to assess the temporal trend, in addition to their relationships with environmental factors. Phytoplankton alpha diversity in the Upper Paraná River floodplain ranged between 4 and 87 species and showed a mean of 30 (±16.5). Sites associated with the Paraná River showed a decline in diversity, which was associated with transparency, nitrogen and phosphorus forms. These results reflect a combination of seston retention by damming and an increase in the N:P ratio, which appears to negatively affect phytoplankton diversity. If temporal trends in environmental variation and the phytoplankton community remain, the future consequences for phytoplanktonic diversity in the Paraná subsystem will be severe, which might cause changes in the trophic structure and dynamics, and therefore in the functioning of environments, since this community is one of the main sources of energy for other trophic levels.     

Microzooplankton as an indicator of environmental quality at an industrial complex in the Brazilian Amazon

The large volume of water in the Pará River, together with governmental incentives, has attracted many industries to the city of Barcarena, Brazil. This industrial activity has the potential to cause changes to aquatic environments. Zooplankton species are considered good indicators of environmental changes. We assessed the association between changes in community composition and proximity to an industrial-port complex, and identified potential bioindicator species in these environments. Five quarterly sampling points were selected along the Pará River (P1–P5) in 2012. The zooplankton community in this region is composed of 64 species. The highest total densities were recorded in February and November, which are both during the rainy season. Zooplankton density was greatest at P3, which was near an industrial-port complex, suggesting that industrial activity affected zooplankton density. An IndVal test showed the rotifer Filinia opoliensis (r = 0.86, p = 0.02) to be a possible bioindicator of environmental quality in the study area. This paper contributes to the discussion of the impacts of installing industrial plants and large ports in the Amazon.     

Occult haemoglobin in fish skin mucus as an indicator of early stress

Early induced stress may result in the release of free haemoglobin into the skin mucus of teleostean fishes. If this were the case, it could be indicated quickly and simply by the colour change of a commercially available haemoglobin test strip. Preliminary tests on Mugil cephalus (grey mullet) encouraged more extensive investigations with Chanos chanos (milkfish), Caranx ignobilis (papio), Albula vulpes (bonefish), and Chaetodon miliaris (butterfly fish). The results indicated that unstressed individuals of these species have no detectable haemoglobin in their skin mucus but, within 2–4 min, the pigment will appear in occult amounts if stress is applied. Additional studies confirmed that it was haemoglobin and no other possible contaminants in the mucus which caused the colour change of the test strip.
The technique is simple and quick, and is itself harmless to the fish. It is of immediate potential value to fish culturists for the detection of early stress conditions. Efforts can then be made to lessen or remove the stress conditions before debility and possibly overt disease take over. A further application of the technique may be the identification of individuals genetically better able to resist disease.     

Caution for using ventilatory frequency as an indicator of stress in fish

This study tested the use of ventilatory frequency (VF) as an indicator of stress in the Nile tilapia, Oreochromis niloticus (L.). Firstly, we tested the relationship between VF and plasma cortisol after confinement. Confined fish showed higher VF and plasma cortisol levels, but the latter continued to increase significantly for longer time than VF. Secondly, we conducted another experiment to test the use of VF as indicator of fish stress. In four out of six treatment, we confined the fish for different intervals (30 s, 5, 15 or 30 min). The others were used as control. In one, no handling was imposed. The other control consisted of introducing the partition (the same used to perform the confinement) into the aquarium for less than 4 s, without confinement and immediately removing the partition (partition control). Ventilatory frequency was increased for the partition control as much as for the longer duration of confinement. This clearly indicates that VF is a very sensitivity response to disturbance, but of limited use because this parameter does not reflect the severity of the stimulus. Thus, although VF is a non-invasive technique that does not require sophisticated recording equipment, its usefulness is limited.