The Hertz Corporation

About: The Hertz Corporation is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 9562 authors who have published 11044 publications receiving 447929 citations. The organization is also known as: Hertz Rental Car & Hertz Rent-a-Car.

Turnover of biomass C and P in soil following incorporation of glucose or ryegrass

Abstract: The turnover times of soil microbial biomass carbon (biomass C) and phosphorus (biomass P) were estimated from the declines in biomass 14C and 32P following the addition to soil of 14C-labelled glucose with added KH232PO4 or with the separate addition of ryegrass which had been doubly labelled with 14CO2 and KH232PO4 (both at 1000 μg C and about 10 μg added P g−1 soil). The labelled substrates were added separately to an UK grassland soil which was then incubated for 60 days at 25 °C and 40% water holding capacity. Addition of 32P caused a considerable displacement (up to 60%) of non-labelled P in the biomass of soils also given glucose. There was also significant displacement of non-labelled biomass P in soils given 32P only. With ryegrass, the labelled P addition increased the total biomass P pool size, rather than displacing native biomass P. However, with biomass C the increase in total biomass C pool size was larger than the displacement of original biomass C at this relatively low addition of substrate C. Under the above incubation conditions biomass C had a turnover time of about 82 days for glucose and 95 days for ryegrass. The turnover times of biomass P for glucose was about 37 and 42 days for ryegrass. The much shorter turnover time of biomass P than C may be because P is much more labile within the microbial cell than C. For example, unlike C, little P is generally located in the cell walls of micro-organisms, which turnover more slowly than the cytoplasmic components. These results illustrate the large potential of biomass P turnover as a source of P for plants, particularly in ‘low input’ systems.

A new look at thrips (Thysanoptera) mouthparts, their action and effects of feeding on plant tissue

Abstract: To elucidate how thrips feed, the mouthparts of Limothrips cerealium (Hal.) were examined in dead specimens by scanning electron microscopy and plasma-ashing, and in living specimens by cinematography as individuals fed through a transparent membrane on clear liquid containing small polystyrene latex particles that made its flow visible. Close contact with the food substrate was maintained by the labral pad. The single mandible was used to pierce the membrane and was then withdrawn rapidly and replaced by the maxillary stylets, which formed a tube with either a terminal or sub-terminal opening into which food was drawn by cibarial pumping at 2–6 pulsations/s. Oscillations in the surrounding fluid caused by such pumping were detectable up to 58 μm from the maxillary opening. Feeding persisted from a few seconds to up to half an hour, and when complete the stylets were withdrawn either rapidly and together, or more gradually by sliding one against the other. Whole chloroplasts up to 6 μm in diameter were ingested even though the diameter of the maxillary tube was about 1 μm. The thrips consumed the contents of ruptured plant cells at about 8·5 × 1O-5 μl/min, equivalent to almost 12·5% of their body weight per hour. Probing and feeding removed the surface wax from leaves, and the cuticle was so exposed that it often wrinkled. Leaf cells beneath a pierced epidermal cell were usually emptied completely, and little seepage from the wounded tissue occurred after stylet withdrawal. After intensive feeding, many mesophyll cells were totally destroyed and others showed extreme plasmolysis; grana sacks were contorted and large starch grains formed due to desiccation. Above such internal damage the epidermal cells collapsed, and the outer cuticle wrinkled and appeared silvery before turning yellow and brown.

Relationship between amount of esterase and gene copy number in insecticide-resistant Myzus persicae (Sulzer).

Abstract: Overproduction of the insecticide-degrading esterases, E4 and FE4, in peach-potato aphids, Myzus persicae (Sulzer), depends on both gene amplification and transcriptional control, the latter being associated with changes in DNA methylation. The structure and function of the aphid esterase genes have been studied but the determination of their copy number has proved difficult, a common problem with gene amplification. We have now used a combination of pulsed-field gel electrophoresis and quantitative competitive PCR to determine relative esterase gene copy numbers in aphid clones with different levels of insecticide resistance (R1, R2 and R3). There are approx. 4-fold increases between susceptible, R1, R2 and R3 aphids, reaching a maximum of approx. 80 times more genes in R3; this gives proportionate increases in esterase protein relative to susceptible aphids. Thus there is no overexpression of the amplified genes, in contrast with what was thought previously. For E4 genes, the loss of 5-methylcytosine is correlated with a loss of expression, greatly decreasing the amount of enzyme relative to the copy number.

Myocet (liposome-encapsulated doxorubicin citrate): a new approach in breast cancer therapy

Abstract: Doxorubicin, either as a single agent or in combination regimens, is considered to be one of the most active chemotherapeutic agents in the treatment of metastatic breast cancer. However, its clinical utility is limited by a cumulative, dose-dependent cardiac myopathy that can lead to potentially fatal congestive heart failure. Considerable research has gone into improving the therapeutic index of doxorubicin-based regimens. A new liposomal formulation of doxorubicin (Myocet™, Elan Pharmaceuticals) has a significantly improved therapeutic index compared with conventional doxorubicin. The development of Myocet, a less cardiotoxic, better tolerated and equally efficacious doxorubicin, extends the therapeutic options in the overall management of breast cancer.

EP4 prostanoid receptor-mediated vasodilatation of human middle cerebral arteries

Abstract: 1 Dilatation of the cerebral vasculature is recognised to be involved in the pathophysiology of migraine. Furthermore, elevated levels of prostaglandin E2 (PGE2) occur in the blood, plasma and saliva of migraineurs during an attack, suggestive of a contributory role. In the present study, we have characterised the prostanoid receptors involved in the relaxation and contraction of human middle cerebral arteries in vitro. 2 In the presence of indomethacin (3μM) and the TP receptor antagonist GR32191 (1 μM), PGE2 was found to relax phenylephrine precontracted cerebral arterial rings in a concentration-dependent manner (mean pEC50 8.0 ± 0.1, n = 5). 3 Establishment of a rank order of potency using the EP4 > EP2 agonist 11-deoxy PGE1, and the EP2 > EP4 agonist PGE1-OH (mean pEC 50 of 7.6 ± 0.1 (n = 6) and 6.4 ± 0.1 (n = 4), respectively), suggested the presence of functional EP4 receptors. Furthermore, the selective EP2 receptor agonist butaprost at concentrations < 1 μM failed to relax the tissues. 4 Blockade of EP 4 receptors with the EP4 receptor antagonists AH23848 and EP4A caused significant rightward displacements in PGE2 concentration-response curves, exhibiting pA2 and pKB values of 5.7 ± 0.1, n = 3, and 8.4, n = 3, respectively. 5 The IP receptor agonists iloprost and cicaprost relaxed phenylephrine precontracted cerebral arterial rings (mean pEC50 values 8.3 ± 0.1 (n = 4) and 8.1 ± 0.1 (n = 9), respectively). In contrast, the DP and FP receptor agonists PGD2 and PGFα2 failed to cause appreciable relaxation or contraction at concentrations of up to 30 μM. In the absence of phenylephrine contraction and GR32191, the TP receptor agonist U46619 caused concentration-dependent contraction of cerebral artery (mean pEC50 7.4 ± 0.3, n = 3). 6 These data demonstrate the presence of prostanoid EP4 receptors mediating PGE2 vasodilatation of human middle cerebral artery. IP receptors mediating relaxation and TP receptors mediating contraction were also functionally demonstrated.