Chloroethene biodegradation in sediments at 4 degrees C

Microbial reductive dechlorination of [1,2-14C]trichloroethene to [14C]cis-dichloroethene and [14C]vinyl chloride was observed at 4 degrees C in anoxic microcosms prepared with cold temperature-adapted aquifer and river sediments from Alaska. Microbial anaerobic oxidation of [1,2-14C]cis-dichloroethene and [1,2-14C]vinyl chloride to 14CO2 also was observed under these conditions.     

Muscle glycogen depletion during exercise at 9 degrees C and 21 degrees C

This study compared glycogen depletion in active skeletal muscle after light and moderate exercise in both cold and comfortable ambient conditions. Twelve male subjects (Ss) were divided into two groups equally matched for the submaximal exercise intensity corresponding to a blood lactate concentration of 4 mM (W4) during cycle exercise. On two separate days Ss rested for 30 min at ambient temperatures of either 9 degrees C or 21 degrees C, with the order of temperature exposure being counter-balanced among Ss. Following rest a tissue specimen was obtained from the m. vastus lateralis with the needle biopsy technique. Six Ss then exercised on a cycle ergometer for 30 min at 30% W4 (range = 50 - 65 W) while the remaining group exercised at 60% W4 (range = 85 - 120 W). Another biopsy was taken immediately after exercise and both samples were assayed for glycogen content. Identical procedures were repeated for the second environmental exposure. No significant glycogen depletion was observed in the Ss exercising at 30% W4 in 21 degrees C, but a 23% decrease (p = 0.04) was observed when the same exercise was performed at 9 degrees C. A 22% decrease (p = 0.002) in glycogen occurred in the 60% W4 group at 21 degrees C, which was not significantly different from that observed during the same exercise at 9 degrees C. The results suggest that muscle substrate utilization is increased during light exercise in a cold environment as compared to similar exercise at a comfortable temperature, probably due to shivering thermogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in the rheologic properties of various samples of blood preserved at +4 degrees C

Apparent stationary viscosity, viscoelasticity and thixotropy measured with a Couette viscosimeter have been determined on blood samples stored in eight anticoagulant and/or preservative solutions. All the results as well as those obtained in a previous morphological study show clearly the advantages of the SAG or PAGGS storage processes. It is observed that the rheological parameters of RBC stored in protein poor media are, between the 30 th and 35 th days, identical on CPD at the first week and with that measured in CPD concentrates between second and third week (for a same hematocrit value). We want to emphasize that the erythrocytes stored in these new media retain for a long time their ability to circulate in the capillary system.     

Survival of bovine embryos stored at 4 degrees C

These experiments were designed to test the efficacy of storing bovine embryos at 4 degrees C. Of particular interest were the age of embryo at which maximum post-storage survival could be achieved and longevity at 4 degrees C. A greater proportion of day 8 blastocysts developed in vitro at 37 degrees C following refrigeration for 48 hr than did embryos collected 2, 4 or 6 days after estrus (P<0.01). Survival of blastocysts stored at 4 degrees C for 48 hr was similar to that of nonstored blastocysts. In a subsequent experiment, day 8 blastocysts were recovered nonsurgically and assigned to one of the following treatments: (a) immediate transfer; (b) culture at 37 degrees C; or (c) storage at 4 degrees C for 1, 2, 3 or 5 days. Post-storage viability was assessed by either development in culture at 37 degrees C or embryo survival following nonsurgical transfer to synchronized recipients. In vitro survival of nonstored embryos and embryos stored 1 day did not differ. Survival decreased after storage for 2 days (P<0.10) or longer (P<0.05). Similar results were observed for survival after transfer, but embryo viability decreased even more rapidly with increasing duration of storage. In vitro survival was approximately 50% for blastocysts stored for 3 and 5 days, but few pregnancies resulted from transfer of embryos stored for these periods. In another experiment survival after transfer of blastocysts stored at 4 degrees C for up to 2 days was similar to that of nonstored blastocysts.     

Short-term storage of rabbit embryos at 4 degrees C

A simple method for storing preimplantation mammalian embryos was tested under conditions which could be easily maintained inside an ordinary refrigerator set at 4 degrees C. No significant loss of viability occurred when rabbit embryos were stored at 4 degrees C for 7 days and either cultured in vitro at 37 degrees C or transferred to recipient does. Significant losses occurred when embryos were stored for 10 days or longer before culture at 37 degrees C (P < .01). Stored embryos transferred to recipients had a significantly longer average gestation period than embryos transferred without cold storage (P < .05).     

Modern Subsurface Bacteria in Pristine 2.7 Ga-Old Fossil Stromatolite Drillcore Samples from the Fortescue Group,Western Australia

Background

Several abiotic processes leading to the formation of life-like signatures or later contamination with actual biogenic traces can blur the interpretation of the earliest fossil record. In recent years, a large body of evidence showing the occurrence of diverse and active microbial communities in the terrestrial subsurface has accumulated. Considering the time elapsed since Archaean sedimentation, the contribution of subsurface microbial communities postdating the rock formation to the fossil biomarker pool and other biogenic remains in Archaean rocks may be far from negligible.

Methodology/Principal Findings

In order to evaluate the degree of potential contamination of Archean rocks by modern microorganisms, we looked for the presence of living indigenous bacteria in fresh diamond drillcores through 2,724 Myr-old stromatolites (Tumbiana Formation, Fortescue Group, Western Australia) using molecular methods based on the amplification of small subunit ribosomal RNA genes (SSU rDNAs). We analyzed drillcore samples from 4.3 m and 66.2 m depth, showing signs of meteoritic alteration, and also from deeper “fresh” samples showing no apparent evidence for late stage alteration (68 m, 78.8 m, and 99.3 m). We also analyzed control samples from drilling and sawing fluids and a series of laboratory controls to establish a list of potential contaminants introduced during sample manipulation and PCR experiments. We identified in this way the presence of indigenous bacteria belonging to Firmicutes, Actinobacteria, and Alpha-, Beta-, and Gammaproteobacteria in aseptically-sawed inner parts of drillcores down to at least 78.8 m depth.

Conclusions/Significance

The presence of modern bacterial communities in subsurface fossil stromatolite layers opens the possibility that a continuous microbial colonization had existed in the past and contributed to the accumulation of biogenic traces over geological timescales. This finding casts shadow on bulk analyses of early life remains and makes claims for morphological, chemical, isotopic, and biomarker traces syngenetic with the rock unreliable in the absence of detailed contextual analyses at microscale.     

Fertility of mouse spermatozoa retrieved from cadavers and maintained at 4 degrees C

After male animals die, the spermatozoa within the testis and epididymis eventually disintegrate. In this study, the motility, viability and fertility of mouse spermatozoa were examined after retrieval from the epididymis at various days after death. Cadavers were maintained in a refrigerator at 4 degrees C. About 30% of the spermatozoa collected 10 days after death were viable, but they had limited ability to fertilize oocytes in vitro. However, when the spermatozoa were injected into oocytes, the fertilization rate was over 80%. Normal live fetuses were even obtained using immotile spermatozoa retrieved 20 days after death. Therefore, when valuable male animals die unexpectedly and sperm cryopreservation is not possible immediately, temporal storage of cadavers (or epididymis and vas deferens) at 4 degrees C in a regular refrigerator followed by intracytoplasmic sperm injection may help to preserve the genome of individuals. This procedure could be particularly important in endangered species.     

Translational initiation is uncoupled from elongation at 18 degrees C during mammalian hibernation

Cellular and organismal homeostasis must be maintained across a body temperature (Tb) range of 0 to 37 degrees C during mammalian hibernation. Hibernators depress biosynthetic activities including protein synthesis, concordant with limited energy availability and temperature effects on reaction rates. We used polysome analysis to show that initiation of protein synthesis ceases during entrance into torpor in golden-mantled ground squirrels (Spermophilus lateralis) when Tb reaches 18 degrees C. Elongation of preinitiated polypeptides continues slowly throughout the torpor bout. As Tb begins to rise, initiation resumes even at temperatures below 18 degrees C, although the euthermic polysome pattern is not reestablished. At precisely 18 degrees C, there is a large increase in initiation events and a complete restoration of euthermic polysome distribution patterns. These data indicate a role for both passive and active depression of translation during torpor and are consistent with a requirement for new protein biosynthesis during each interbout arousal.     

Solid Medium for Culturing Black Smoker Bacteria at Temperatures to 120 degrees C

A solid, highly thermostable medium, based on the new gelling agent GELRITE, was devised to facilitate the culturing of extremely thermophilic microorganisms from submarine hydrothermal vents. The medium remained solid at temperatures to 120 degrees C at vapor pressures and hydrostatic pressures to 265 atm. It proved useful to its maximum tested limits in isolating colonies of black smoker bacteria from hydrothermal fluids recently collected at the Juan de Fuca Ridge in the Pacific Ocean.     

Changes in Ester-Linked Phospholipid Fatty Acid Profiles of Subsurface Bacteria during Starvation and Desiccation in a Porous Medium

Ester-linked phospholipid fatty acid (PLFA) profiles of a Pseudomonas aureofaciens strain and an Arthrobacter protophormiae strain, each isolated from a subsurface sediment, were quantified in a starvation experiment in a silica sand porous medium under moist and dry conditions. Washed cells were added to sand microcosms and maintained under saturated conditions or subjected to desiccation by slow drying over a period of 16 days to final water potentials of approximately - 7.5 MPa for the P. aureofaciens and - 15 MPa for the A. protophormiae. In a third treatment, cells were added to saturated microcosms along with organic nutrients and maintained under saturated conditions. The numbers of culturable cells of both bacterial strains declined to below detection level within 16 days in both the moist and dried nutrient-deprived conditions, while direct counts and total PLFAs remained relatively constant. Both strains of bacteria maintained culturability in the nutrient-amended microcosms. The dried P. aureofaciens cells showed changes in PLFA profiles that are typically associated with stressed gram-negative cells, i.e., increased ratios of saturated to unsaturated fatty acids, increased ratios of trans- to cis-monoenoic fatty acids, and increased ratios of cyclopropyl fatty acids to their monoenoic precursors. P. aureofaciens starved under moist conditions showed few changes in PLFA profiles during the 16-day incubation, whereas cells incubated in the presence of nutrients showed decreases in the ratios of both saturated fatty acids to unsaturated fatty acids and cyclopropyl fatty acids to their monoenoic precursors. The PLFA profiles of A. protophormiae changed very little in response to either nutrient deprivation or desiccation. Diglyceride fatty acids, which have been proposed to be indicators of dead or lysed cells, remained relatively constant throughout the experiment. Only the A. protophormiae desiccated for 16 days showed an increase in the ratio of diglyceride fatty acids to PLFAs. The results of this laboratory experiment can be useful for interpreting PLFA profiles of subsurface communities of microorganisms for the purpose of determining their physiological status.     

Short-Term Storage at 4 C of Trypsinized Tissues

Cells dispersed from tissues of certain animals remained viable for several days at 4 C although the per cent of viable cells varied among the different species.     

Species Composition of Cultivated and Noncultivated Bacteria from Short Filaments in an Icelandic Hot Spring at 88 degrees C

Samples of short pink-grayish filaments were collected from a hot spring in the Hengill area in southwestern Iceland at 85-88 degrees C, pH 6.9 and 1.7 mg/L sulfide. The species composition was studied by cloning and sequencing small subunit rRNA genes obtained by PCR amplifications from mat DNA. Using 98% sequence similarity as a cutoff value, a total of 5 bacterial operational taxonomic units (OTUs) and 6 archaeal OTUs were detected among 68 bacterial clones and 97 archaeal clones. Database matching showed that 80.5% of the archaeal sequences were 99% similar to Pyrobaculum islandicum and 14.5% were closest to the Korarchaeota clone sequence SRI306. About 87% of the bacterial sequences had the closest database match (99%) to the clone sequence SRI48 but were also found to be 99% identical with hydrogen-oxidizing strains previously isolated in this laboratory from hot springs in the same region. Out of 7 Thermus sequences, 4 were 100% identical to T. scotoductus NMX2 A.1 but 3 represented a new uncultivated Thermus species. Four different media, varying in organic nutrients and phosphate composition were used to isolate 81 aerobic thermophilic heterotrophs. Four isolates were Bacillus spp; but out of 77 Thermus isolates, 42 belonged to T. scotoductus and 35 to T. brockianus. T. scotoductus seemed to be preferably isolated on media low in nutrients and phosphate, whereas for T. brockianus it was the opposite. The T. scotoductus clones and isolates had 99-100% sequence similarity to each other. No T. brockianus sequences were found in the bacterial clone library.     

Skin preservation at 4 degrees C: a species comparison

There are numerous experimental studies in the literature regarding skin storage and preservation. These studies are difficult to interpret due to the variety of storage techniques utilized and the number of different animal species used as skin donors. This study utilized a single cold storage protocol to test the effect of species variation on skin graft viability. Donor skin was obtained from five animal species and human surgical panniculectomy specimens. The skin was stored in modified Roswell Park Memorial Institute (RPMI) 1640 tissue culture media at 4 degrees C. Stored skin was transplanted to surgically created defects on athymic (nude) mice after specific storage intervals. Ten days after transplantation, the grafts were examined by gross and microscopic techniques. The viability of mouse, rat, and dog skin was significantly different from human skin, while stored rabbit and pig skin were similar to human skin. These results demonstrate the difficulty of applying the data of skin storage studies from nonhuman species to clinical practice. The data indicate that rabbit and pig skin may be used in laboratory studies of skin preservation at 4 degrees C with a strong likelihood that the results may be of clinical relevance in predicting the behavior of human skin under similar storage conditions.     

DHPR activity decrease in dried blood spots stored at 4 degrees C

Dihydropteridine reductase (DHPR) activity has been measured in dried blood spots by the Arai method in 286 subjects divided into 4 groups: 45 newborns aged between 4 and 7 days; 40 subjects with hyperphenylalainaemia; 199 apparently normal subjects, and 2 patients with DHPR deficiency. Furthermore, a study of the persistence of enzymatic activity on the spots stored at 4 degrees C revealed that after 1 year it decreased to one third of the original value, corresponding to the mean value of controls minus 2 SD.     

Antibiotic Resistance in Bacteria Isolated from the Deep Terrestrial Subsurface

Various natural environments have been examined for the presence of antibiotic-resistant bacteria and/or novel resistance mechanisms, but little is known about resistance in the terrestrial deep subsurface. This study examined two deep environments that differ in their known period of isolation from surface environments and the bacteria therein. One hundred fifty-four strains of bacteria were isolated from sediments located 170–259 m below land surface at the US Department of Energy Savannah River Site (SRS) in South Carolina and Hanford Site (HS) in Washington. Analyses of 16S rRNA gene sequences showed that both sets of strains were phylogenetically diverse and could be assigned to several genera in three to four phyla. All of the strains were screened for resistance to 13 antibiotics by plating on selective media and 90% were resistant to at least one antibiotic. Eighty-six percent of the SRS and 62% of the HS strains were resistant to more than one antibiotic. Resistance to nalidixic acid, mupirocin, or ampicillin was noted most frequently. The results indicate that antibiotic resistance is common among subsurface bacteria. The somewhat higher frequencies of resistance and multiple resistance at the SRS may, in part, be due to recent surface influence, such as exposure to antibiotics used in agriculture. However, the HS strains have never been exposed to anthropogenic antibiotics but still had a reasonably high frequency of resistance. Given their long period of isolation from surface influences, it is possible that they possess some novel antibiotic resistance genes and/or resistance mechanisms. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.