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931.
Subterranean or groundwater estuaries occur in porous and cavernous substrates where groundwater abuts the ocean. Like surface
estuaries, they are strongly stratified, temporally and hydrochemically heterogeneous environments that support complex hydrogeochemical
and biological processes and ecological communities. Here, we contend that groundwater estuaries also occur where groundwater
flow approaches salt lakes and provide evidence in the context of groundwater (valley or phreatic) calcretes in palaeovalleys
of the arid western plateau of Australia. The calcrete groundwater estuaries display marked and complex physico-chemical gradients
along, across and through the groundwater flow path. From the first principles and the density differences between water bodies,
we may expect the form and dynamics of the saltwater front to mimic that of marine estuaries but with the dynamic and temporal
response to changing hydrology heavily dampened, and driven by the episodic groundwater recharge and lake filling typical
of arid regions. The calcrete aquifers support diverse biological communities of obligate groundwater animals, largely endemic
to a given calcrete body. These communities comprise both macro and microinvertebrates, predominantly a suite of crustacean
higher taxa, and a great diversity of diving beetles (Dytiscidae) isolated in the calcrete aquifers between ca. 5 and 8 million
years ago.
Guest Editors: J. John & B. Timms
Salt Lake Research: Biodiversity and Conservation—Selected papers from the 9th Conference of the International Society for
Salt Lake Research
An erratum to this article can be found at 相似文献
932.
Reactions of [Pt2(μ-S)2(PPh3)4] with the diarylthallium(III) bromides Ar2TlBr [Ar = Ph and p-ClC6H4] in methanol gave good yields of the thallium(III) adducts [Pt2(μ-S)2(PPh3)4TlAr2]+, isolated as their salts. The corresponding selenide complex [Pt2(μ-Se)2(PPh3)4TlPh2]BPh4 was similarly synthesised from [Pt2(μ-Se)2(PPh3)4], Ph2TlBr and NaBPh4. The reaction of [Pt2(μ-S)2(PPh3)4] with PhTlBr2 gave [Pt2(μ-S)2(PPh3)4TlBrPh]+, while reaction with TlBr3 gave the dibromothallium(III) adduct [Pt2(μ-S)2(PPh3)4TlBr2]+[TlBr4]−. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt2(μ-S)2(PPh3)4TlPh2]BPh4, [Pt2(μ-S)2(PPh3)4TlBrPh]BPh4 and [Pt2(μ-S)2(PPh3)4TlBr2][TlBr4] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt?Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported. 相似文献
933.
Boris F. Krasnikov Chin-Hsiang Chien Regina Nostramo John T. Pinto Edward Nieves Myrasol Callaway Jin Sun Kay Huebner Arthur J.L. Cooper 《Biochimie》2009,91(9):1072-1080
The present report identifies the enzymatic substrates of a member of the mammalian nitrilase-like (Nit) family. Nit2, which is widely distributed in nature, has been suggested to be a tumor suppressor protein. The protein was assumed to be an amidase based on sequence homology to other amidases and on the presence of a putative amidase-like active site. This assumption was recently confirmed by the publication of the crystal structure of mouse Nit2. However, the in vivo substrates were not previously identified. Here we report that rat liver Nit2 is ω-amidodicarboxylate amidohydrolase (E.C. 3.5.1.3; abbreviated ω-amidase), a ubiquitously expressed enzyme that catalyzes a variety of amidase, transamidase, esterase and transesterification reactions. The in vivo amidase substrates are α-ketoglutaramate and α-ketosuccinamate, generated by transamination of glutamine and asparagine, respectively. Glutamine transaminases serve to salvage a number of α-keto acids generated through non-specific transamination reactions (particularly those of the essential amino acids). Asparagine transamination appears to be useful in mitochondrial metabolism and in photorespiration. Glutamine transaminases play a particularly important role in transaminating α-keto-γ-methiolbutyrate, a key component of the methionine salvage pathway. Some evidence suggests that excess α-ketoglutaramate may be neurotoxic. Moreover, α-ketosuccinamate is unstable and is readily converted to a number of hetero-aromatic compounds that may be toxic. Thus, an important role of ω-amidase is to remove potentially toxic intermediates by converting α-ketoglutaramate and α-ketosuccinamate to biologically useful α-ketoglutarate and oxaloacetate, respectively. Despite its importance in nitrogen and sulfur metabolism, the biochemical significance of ω-amidase has been largely overlooked. Our report may provide clues regarding the nature of the biological amidase substrate(s) of Nit1 (another member of the Nit family), which is a well-established tumor suppressor protein), and emphasizes a) the crucial role of Nit2 in nitrogen and sulfur metabolism, and b) the possible link of Nit2 to cancer biology. 相似文献
934.
935.
Molly Elizabeth Cummings Rose Gelineau-Kattner 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(10):935-946
The coexistence of alternative male mating strategies depends on the balance between costs and benefits. Here we examine the
short-term metabolic costs associated with distinct reproductive strategies in the genetically determined alternative male
phenotypes of a northern swordtail, Xiphophorus nigrensis. In this species, large males court females, non-adorned small males chase females, and intermediate males exhibit both courtship
and chase behaviors. Using intermittent flow respirometry, we measure oxygen consumption rates and behaviors of each size
class in isolation and in the presence of a female. Changes in oxygen consumption between solitary and female presence trials
(ΔVO2) correlated significantly with standard length across all size classes (r = 0.42). Only the large male class exhibited a significant increase in oxygen consumption in female-present trials exhibiting
a range of increase from 2 to 200% relative to solitary metabolic rates, but costs of specific courtship displays could not
be demonstrated. Sword length explained 54–57% of the variation in oxygen consumption in large male solitary trials and 63–65%
in the female-present trials independent of any behavioral correlation with sword length. Our results exhibit similarities
to condition-dependent alternative mating systems where the female-favored phenotype has higher energetic costs. 相似文献
936.
Christine Elizabeth Cooper Ariovaldo P. Cruz-Neto 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(6):773-781
The honey possum is the only non-volant mammal to feed exclusively on a diet of nectar and pollen. Like other mammalian and
avian nectarivores, previous studies indicated that the honey possum’s basal metabolic rate was higher than predicted for
a marsupial of equivalent body mass. However, these early measurements have been questioned. We re-examined the basal metabolic
rate (2.52 ± 0.222 ml O2 g−1 h−1) of the honey possum and confirm that it is indeed higher (162%) than predicted for other marsupials both before and after
accounting for phylogenetic history. This, together with its small body mass (5.4 ± 0.14 g; 1.3% of that predicted by phylogeny)
may be attributed to its nectarivorous diet and mesic distribution. Its high-basal metabolic rate is associated with a high-standard
body temperature (36.6 ± 0.48°C) and oxygen extraction (19.4%), but interestingly the honey possum has a high point of relative
water economy (17.0°C) and its standard evaporative water loss (4.33 ± 0.394 mg H2O g−1 h−1) is not elevated above that of other marsupials, despite its mesic habitat and high dietary water intake. 相似文献
937.
S. Devin McLennan Lauren A. Peterson Joan B. Rose 《Applied and environmental microbiology》2009,75(22):7283-7286
Four point-of-use disinfection technologies for treating sewage-contaminated well water were compared. Three systems, based on flocculant-disinfectant packets and N-halamine chlorine and bromine contact disinfectants, provided a range of 4.0 to >6.6 log10 reductions (LR) of naturally occurring fecal indicator and heterotrophic bacteria and a range of 0.9 to >1.9 LR of coliphage.Disasters and flooding can overwhelm sanitation infrastructure, leading to sewage contamination of potable waters. This may be routine during the wet season in many parts of the world and spreads numerous waterborne diseases (21). Point-of-use (POU) water treatment has reduced the incidence of diarrheal disease when used for household drinking water (3, 4, 6, 13) and is now being promoted for disaster relief. While POU systems have recently been reviewed (14), to our knowledge there has been no direct, experimental comparison for treating actual sewage-contaminated waters. In this study, the efficacies of four POU disinfection systems (based on sodium dichloroisocyanurate [NaDCC] tablets, a flocculent-disinfectant powder, and chlorine and bromine contact disinfectant cartridges) in reducing the concentrations of six microbial indicators in well water contaminated with raw sewage were compared.The NaDCC tablets (67 mg; Aquatabs; Medentech, Wexford, Ireland), used for disinfection in low-turbidity water, have shown preliminary efficacy for routine household drinking water treatment (3, 4). The flocculant-disinfectant packet (4 g; PUR; Procter & Gamble Co., Cincinnati, OH) includes Fe2(SO4)3, bentonite, Na2CO3, chitosan, polyacrylamide, KMnO4, and Ca(OCl)2 (13). It achieved >7.3 log10 reductions (LR) of 24 bacteria species; >4.6 LR of poliovirus and rotavirus in EPA no. 2 test water (turbidity, >30 nephelometric turbidity units [NTU]) (15); and reduced diarrheal illness in Guatemala, Liberia, Kenya, and Pakistan (6, 7, 11, 13).HaloPure canisters (Eureka Forbes, Mumbai, India) contain N-halamine polymer disinfectant beads, poly[1,2-dichloro-5-methyl-5-(4′-vinylphenyl)hydrantoin] for chlorine canisters, and poly[1,2-dibromo-5-methyl-5-(4′-vinylphenyl)hydrantoin] for bromine canisters. Seeded laboratory trials achieved >6.8 LR for Escherichia coli and Staphylococcus aureus as water was passed through the canisters (2). The Cl-contact (producing residuals ranging from 0 to 0.6 mg/liter) and Br-contact (with residuals of 0.68 to 1.8 mg/liter) disinfectants achieved 2.9 LR and 5.0 LR of the bacteriophage MS2, respectively, and 27.5% and 88.5% reductions of the algal toxin microcystin, respectively (5).Sewage-contaminated water was prepared by mixing 9 liters of potable, nonchlorinated well water (pH 7.8; turbidity, 0.33 NTU; Williamston, MI) with 1 liter of raw sewage (City of East Lansing Wastewater Treatment Plant, MI) with an average pH of 6.6 ± 0.1, a biochemical oxygen demand of 144 ± 36 mg/liter, a concentration of total suspended solids of 146 ± 31 mg/liter, and a turbidity of 132 ± 12 NTU. Three disinfection trials were conducted at room temperature for each POU system on three different days to allow for variance in sewage strength. The turbidities of 1:10 dilutions of raw sewage averaged 7.5 ± 2.0 NTU. Table Table11 lists the indicator microorganism concentrations in the influent and effluent for each system.
Open in a separate windowaValues shown are numbers of CFU/ml except those for coliphage, which are numbers of PFU/ml. The percentage of samples below the detection limit (n = 3 for all systems) is 0% if not shown.All systems were used in accordance with the manufacturer''s directions for 10 liters of water. For NaDCC trials, one tablet was added and allowed 30 min of contact time (total dose of 3.2 mg/liter of hypochlorite; in deionized water, one tablet produced 2.1 mg/liter free Cl residual). For flocculant-disinfectant trials, one packet was added, stirred vigorously for 5 min, strained through cheesecloth after 10 min, and allowed 20 min of further contact time. The amount of hypochlorite included in one packet was not indicated, but one packet provided 1.5 mg/liter free Cl residual in 10 liters of deionized water. Samples were taken at 1, 3, 5, 10, 15, and 30 min for both systems.For the Cl-contact and Br-contact trials, disinfectant cartridges were installed in AquaSure housings consisting of an upper reservoir for influent, which flows by gravity through the disinfectant cartridge to a lower reservoir with a tap for dispensing (Fig. (Fig.1).1). The housings usually include cloth and activated charcoal prefilters, but these were removed in order to directly evaluate the disinfectant. With the tap open, 10 liters of influent was added and samples were collected at first flow (6 to 12 min) and after 15 and 30 min of flow. A single chlorine canister was used for all trials; the bromine canister was replaced for the third trial because the original clogged.Open in a separate windowFIG. 1.Flow schematic for contact disinfectant cartridges. Arrows indicate the directions of water flow from the upper reservoir (U), through the halogen (chlorine or bromine) disinfectant cartridge (H) containing packed N-halamine beads (N), to the lower reservoir (L) and out through the open tap.Microbial indicators in the influent and effluent (collection tubes contained sodium thiosulfate) in triplicate were quantified as numbers of CFU/ml by using mENDO agar for total coliforms (9), mHPC agar for heterotrophic plate counts (8), mTEC medium for E. coli (19), mEI agar for the genus Enterococcus (18), and mCP agar for the genus Clostridium (1) (Becton, Dickinson and Co., Franklin Lakes, NJ). Coliphage (PFU/ml) were measured with a double agar overlay assay, EPA method 1601 (17). Residuals (mg/liter) were measured using a Hach chlorine (free and total) test kit, model CN66 (Hach Co., Loveland, CO) (used for bromine in accordance with Hach method 8016 [10], with the instrument reading multiplied by 2.25 [the ratio of the atomic weights of bromine and chlorine], as advised by Hach Co. technical support).Comparison of water quality levels was done at 30 minutes. LR were calculated, with zeros replaced with the detection limits (Fig. (Fig.2).2). All POU systems reduced microbial concentrations below the detection limit in some trials (Table (Table1),1), making the calculated reductions the lower bound for those trials.Open in a separate windowFIG. 2.Average LR of naturally occurring microorganisms at 30 min for sewage-contaminated well water (1:10 dilution of raw sewage in well water) with the use of four POU disinfection systems (error bars represent 1 standard error). * indicates that effluent was below the limit of detection for all samples. Limit of detection was substituted to calculate LR and actual reductions may be greater than shown.Average LR for each POU system were compared using two-way analysis of variance with post hoc least-significant-difference (LSD) tests, performed with SPSS 11.0.1 (SPSS, Inc.). LR at 30 min differed significantly between systems (analysis of variance; F3,5 = 20.6; P < 0.001). There was no significant difference between the LR achieved by flocculant-disinfectant and contact disinfectants (LSD; mean difference, 0.2 to 0.5 LR; P > 0.05), while the NaDCC tablets induced significantly lower reductions (LSD; mean difference, 1.5 to 2.0 LR; P < 0.001).There was detectable residual free chlorine after 30 min for one NaDCC trial (0.4 mg/liter) and two flocculant-disinfectant trials (0.1 and 0.4 mg/liter). No contact disinfectant trial produced a measurable residual.No system in this study reliably produced residuals for safe storage after POU treatment or ideal virus reduction. Except for the NaDCC system, the POU systems achieved approximately 5.5 LR for E. coli and coliforms, 4.5 LR for enterococci, 4.0 LR for heterotrophs, 2.5 LR for clostridia, and 1.0 LR for coliphage. Coliphage was reduced below detection limits in all trials with Br-contact, similar to what was found in previous research (5). Bromine disinfection has proved safe and effective for large-scale maritime applications, like U.S. Navy vessels (20), and appears promising for household treatment. Further assessment of the Br-contact system is warranted, as is field comparison of POU systems in disaster relief. 相似文献
TABLE 1.
Concentrations of influent and 30-min-effluent microorganisms for POU disinfectant systems treating sewage-contaminated waterMicroorganism group | Geometric mean concn (range) [% of samples below detection limit]a | |||||||
---|---|---|---|---|---|---|---|---|
NaDCC | Flocculant-disinfectant | Cl-contact | Br-contact | |||||
Influent | Effluent at 30 min | Influent | Effluent at 30 min | Influent | Effluent at 30 min | Influent | Effluent at 30 min | |
Total coliforms | 2.7 × 104 (6.7 × 103 to 7.6 × 104) | 4.3 (4.0 × 10−2 to 1.6 × 102) | 1.7 × 104 (1.2 × 104 to 2.7 × 104) | 4.0 × 10−2 (<1.0 × 10−2 to 2.4 × 10−1) [33] | 2.9 × 104 (2.3 × 104 to 4.0 × 104) | <1.0 × 10−2 [100] | 4.5 × 104 (1.9 × 104 to 7.2 × 104) | 1.1 × 10−2 (<1.0 × 10−2 to 1.3 × 10−2) [66] |
Heterotrophic plate counts | 8.7 × 104 (2.7 × 104 to 1.8 × 105) | 6.4 × 101 (2.1 × 101 to 4.5 × 102) | 8.9 × 104 (2.9 × 104 to 4.3 × 105) | 8.5 (4.7 to 2.7 × 101) | 6.6 × 104 (3.5 × 104 to 1.1 × 105) | 3.9 (3.5 to 4.2) | 8.3 × 104 (2.4 × 104 to 2.0 × 105) | 4.6 (2.2 to 7.7) |
E. coli | 3.3 × 103 (7.7 × 102 to 1.1 × 104) | 1.8 × 101 (9.0 × 10−1 to 5.3 × 102) | 6.7 × 103 (2.3 × 103 to 4.3 × 104) | 1.1 × 10−2 (<1.0 × 10−2 to 1.3 × 10−2) [66] | 4.7 × 103 (2.3 × 103 to 1.1 × 104) | <1.0 × 10−2 [100] | 1.5 × 104 (6.3 × 103 to 4.6 × 104) | <1.0 × 10−2 [100] |
Enterococci | 8.8 × 102 (5.7 × 102 to 1.3 × 103) | 2.3 (<1.0 × 10−2 to 4.9 × 101) [33] | 6.3 × 102 (5.0 × 102 to 8.7 × 102) | <1.0 × 10−2 [100] | 9.9 × 102 (5.3 × 102 to 1.7 × 103) | <1.0 × 10−2 [100] | 1.3 × 103 (7.3 × 102 to 2.3 × 103) | <1.0 × 10−2 [100] |
Clostridia | 1.6 × 102 (6.0 × 101 to 3.0 × 102) | 6.4 (6.7 × 10−1 to 7.7 × 101) | 2.0 × 102 (7.0 × 101 to 6.0 × 102) | 7.9 × 10−1 (4.5 × 10−1 to 1.4) | 3.4 × 101 (2.0 × 101 to 6.3 × 101) | 2.4 × 10−2 (<1.0 × 10−2 to 6.0 × 10−2) [33] | 4.4 × 101 (2.7 × 101 to 9.3 × 101) | 7.4 × 10−2 (<1.0 × 10−2 to 3.6 × 10−1) [33] |
Coliphage | 1.5 × 102 (1.2 × 102 to 2.2 × 102) | 3.1 × 101 (<1.0 to 1.8 × 102) [33] | 1.4 × 102 (1.3 × 102 to 1.4 × 102) | 1.9 × 101 (<1.0 to 1.1 × 102) [33] | 9.4 × 101 (4.3 × 101 to 1.6 × 102) | 7.3 (1.3 to 4.7 × 101) | 7.7 × 101 (4.0 × 101 to 1.2 × 102) | <1.0 [100] |
938.
939.
940.