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Ion pair receptors typically contain two separate binding sites, for the metal and the anion respectively. Here we report a less synthetically demanding approach, whereby we prepared a family of ion pair sensors based on a rhodamine fluorescent scaffold containing a tunable cation binding motif. When exposed to ion pairs, a competition for the metal ion is established between these ligands and anions. Structural and spectroscopic evidence showed that anions bind through weaker secondary interactions in the metal's outer coordination sphere and their presence influences the optical spectroscopic properties of the coordination complex in distinctive ways. The relationship between the binding site's metal affinity and its tunable properties, and the sensors' discriminatory power for anions was explained as a function of the metal ion's binding preferences. These effects were also exploited to discriminate cations and anions concurrently through multivariate data analysis methods.

A rhodamine-based chemosensor was synthesized and found to selectively bind ferric ions over other metal ions (Na+, K+, Ca2+, Mg2+, Fe2+, Zn2+, Cd2+, Co2+, Hg2+ Cr3+, Al3+) in an organic-aqueous mi...

The role of iron (+2 and +3 oxidation states) in biological and medical applications and the environment is pivotal. Supramolecular analytical approaches to monitor and remediate iron, in particular, ferric ions (Fe3+) are an area of interest. The development of fluorescence chemosensors using supramolecular chemistry seems to have exponentially grown since the beginning of the twenty-first century. This article will focus on the chemodosimeter and chemoreactand approach which have been developed to target ferric ions. This review will focus on two broad areas; the first section will discuss the ‘traditional’ approach, i.e. small molecule recognition, in organic, mixed organic-aqueous and buffer-aqueous solutions. The second section will highlight the molecular sensors that have been either doped or attached to surfaces to prepare nano-chemical sensors.

Fluorescence sensing, of d-block elements such as Cu2+, Fe3+, Fe2+, Cd2+, Hg2+, and Zn2+ has significantly increased since the beginning of the 21st century. These particular metal ions play essential roles in biological, industrial, and environmental applications, therefore, there has been a drive to measure, detect, and remediate these metal ions. We have chosen to highlight the low molecular weight fluorescent probes (LMFPs) that undergo an optical response upon coordination with the group 12 triad (Zn2+, Cd2+, and Hg2+), as these metals have similar chemical characteristics but behave differently in the environment.

The objective of this study was to evaluate the composting potential of various bedding materials that were previously used in experimental compost bedded packs for dairy cows. Each material was placed in windrows (1.8 m high, 9.1 m long, and 2.3 m wide) from April 2007 to September 2007 and managed as needed to promote composting. Materials included: sawdust (SD) (control), corn cobs (CC), wood chip fines/sawdust mix (WC/SD), soybean straw (SS), wood chip fines/soybean straw mix (WC/SS), and soybean straw/sawdust mix (SS/SD). Replicated samples were taken weekly and analyzed for dry matter (DM). Carbon:nitrogen ratio (C:N ratio), pH, total C, total N, NH4-N, and NO3-N were measured once monthly. Temperature was measured twice weekly. Total P, total K, and EC were measured at the beginning and end of the composting period. Windrow temperatures exceeded 55°C for 10 to 96 days, and coliform populations were reduced from 106 or 107 to 500 cfu/mL or fewer in all materials. CC, SS/WC, WC/SS, and SS were the only materials that decreased (P < 0.05) in moisture content from day 0 to day 138. Materials were similar when comparing day 0 and day 138 for NH4-N, total N, and inorganic N concentrations. SS, SS/SD, WC/SS, and WC/SD all decreased in total C and C:N ratio(P < 0.05) from day 0 to day 138. C:N ratios were below 20:1 at the end of the composting period, with the exception of SD and WC/SD. Based on these results, all materials composted during the time period and would potentially work as a soil amendment/mulch if proper composting takes place.

Jersey (JE)×Holstein (HO) crossbred cows (n=76) were compared with pure HO cows (n=73) for 305-d milk, fat, and protein production, somatic cell score (SCS), clinical mastitis, lifetime production, and body measurements during their first 3 lactations. Cows were in 2 research herds at the University of Minnesota and calved from September 2003 to June 2008. Best prediction was used to determine actual production for 305-d lactations as well as lifetime production (to 1,220 d in the herd after first calving) from test-day observations. During first lactation, JE×HO cows and pure HO cows were not significantly different for fat plus protein production; however, JE×HO cows had significantly lower fat plus protein production during second (-25 kg) and third (-51 kg) lactation than pure HO cows. Nevertheless, JE×HO cows were not significantly different from pure HO cows for lifetime production or lifetime SCS. The JE×HO cows were not significantly different from pure HO cows for SCS and clinical mastitis during first and second lactations; however, JE×HO cows tended to have higher SCS (3.79) than pure HO cows (3.40), but significantly lower (-23.4%) clinical mastitis during third lactation. The JE×HO cows had significantly less hip height, smaller heart girth, less thurl width, and less pin width than pure HO cows during the first 3 lactations. Furthermore, JE×HO cows had significantly less udder clearance from the ground and significantly greater distance between the front teats than pure HO cows during their first 3 lactations.

Dans cet article, nous donnons les bases d'une theorie sur la generation des l-groupes et des f-anneaux reduits a partir de certaines sous-structures. Nous sommes concernes en premier lieu par les groupes et anneaux archimediens et hyperarchimediens. Nous discutons le procede d'adjoindre une unite faible a un l-groupe ou une identite a un f-anneau et nous trouvons des differences significatives entre ces situations. Dans les l-groupes, certaines proprietes comme celle d'etre hyperarchimedien ne sont pas toujours transferees aux structures engendrees, comme le montre l'exemple fondamental de Conrad et Martinez, que nous revisitons et elaborons. Par contre, ces proprietes sont transferees dans le cas des f-anneaux reduits.

Availability of bedding material for compost bedded pack barns is a concern for dairy producers who use this type of alternative housing system. The material most commonly used in these barns is dry sawdust. The objective of this descriptive study was to evaluate different types of bedding material that could potentially substitute or partially substitute for sawdust in these housing systems. The study was conducted at the West Central Research & Outreach Center in Morris, Minnesota, from November 2006 to March 2007. Materials included: pine sawdust (control) (SD), corn cobs (CC), pine woodchip fines (WC), and soybean straw (SS). Some of these materials were evaluated as mixtures on a 2:1 volume-to-volume ratio. These mixtures included: woodchips/sawdust (WC/SD), woodchips/soybean straw (WC/SS), and soybean straw/sawdust (SS/SD). Experimental bedded packs were used, each with one of the bedding materials, and 16 cows were placed on each pack. Replicated samples of the bedded pack material were collected twice a month and analyzed for dry matter. C:N ratios and pH were analyzed monthly. Temperatures of each pack were measured weekly at various depths (15.2, 30.5, 45.7, and 61.0 cm). Cows were scored for hygiene (1=clean, 5=dirty) twice a month. Moisture content of SD was 59.7; CC, 44.5; WC/SD, 60.6; SS/SD, 58.2; WC/SS, 60.7; and SS, 60.6. SD pH was 8.7; CC, 7.7; WC/SD, 8.6; SS/SD, 8.6; WC/SS, 8.3; and SS, 8.6. C:N ratio of SD was 37.3; CC, 29.2; WC/SD, 47.5; SS/SD, 25.6; WC/SS, 31.0; and SS, 22.8. Hygiene score of cows on SD was 2.4; CC, 2.7; WC/SD, 2.5; SS/SD, 2.9; WC/SS, 2.6; and SS, 2.8. Based on these results and our observations, it appears that any of the bedding materials evaluated in this study would work in this type of housing system if proper bedding management is applied on a consistent basis. It was concluded that ideal bedding material for compost barns should be dry, processed to less than 2.5 cm long, offer structural integrity, and have good water absorption and holding capacity.

SUMMARYSince 2003, Connecticut laboratories have reported Gram-positive rod (GPR) isolates detected within 32 h of inoculation from blood or cerebrospinal fluid. The objectives were to rapidly identify inhalational anthrax and unusual Clostridium spp. infections, and to establish round-the-clock laboratory reporting of potential indicators of bioterrorism. From 2003 to 2006, Connecticut's GPR surveillance system identified 1134 isolates, including 657 Bacillus spp. (none B. anthracis) and 241 Clostridium spp. Reporting completeness and timeliness improved to 93% and 92%, respectively. Baseline rates of Bacillus spp., Clostridium spp. and other GPR findings have been established and are stable. Thus far, no cases of anthrax and no unusual clusters of Clostridium spp. have been detected by the GPR surveillance system. This system would probably have confirmed the inhalational anthrax case in Pennsylvania in 2006 3 days sooner than traditional reporting. Using audits and ongoing evaluation, the system has evolved into a highly functional 24/7 laboratory telephone reporting system with almost complete reporting.

Jersey x Holstein crossbred (JxH) cows (n = 24) were compared with pure Holstein cows (n = 17) for body weight, body condition score, dry matter intake (DMI), and feed efficiency during the first 150 d of first lactation. Cows were housed in the University of Minnesota dairy facility at the St. Paul campus and calved from September 2004 to January 2005. The JxH cows were mated by artificial insemination with Montbeliarde bulls, and Holstein cows were mated by artificial insemination with Holstein bulls. Cows were weighed and body condition was scored every other week. Cows were individually fed a TMR twice daily, and feed refusals were measured once daily. The DMI of cows was measured daily and averaged across 7-d periods. Milk production and milk composition were from monthly Dairy Herd Improvement records. Best Prediction was used to calculate actual production (milk, fat, protein) for each cow from the 4th to 150th day of first lactation. The JxH cows had significantly less body weight (467 vs. 500 kg) and significantly higher body condition scores (2.90 vs. 2.76) than pure Holstein cows. The JxH cows had significantly less milk production (4,388 vs. 4,644 kg) during the 4th to 150th day of lactation than did pure Holstein cows. However, fat plus protein production during the first 150 d of lactation was not significantly different for JxH (302 kg) and Holstein (309 kg) cows. The JxH and pure Holstein cows did not differ significantly for daily DMI (22.0 vs. 22.7 kg, respectively), and the JxH (4.7%) and pure Holstein (4.5%) cows consumed similar DMI based on percentage of body weight. Consequently, feed efficiency for the 4th to 150th day of lactation did not differ for JxH and pure Holstein cows.

Let frA denote the category of f-rings which are reduced and Archimedean, and let Φ be the (nonfull) subcategory of such rings with identity (each with the natural morphisms). Some time ago, the second author showed, using his representation theory, that for each A ∈ | frA| there is a certain minimal embedding u A :A→ uA ∈ | Φ|. More recently, he has revisited the representation theory, expanding it to include the representation of morphisms. Based upon this, the present article analyzes the operator u:| frA| → Φ: the construction of uA is tidied, several characterizations of the pair (u A , uA) are given, and the relation between the maximal ideal structures of A and uA is described. Membership in the class U of frA-morphisms that are “u-extendable” is characterized and it is shown that U = (| frA|,U) is a category in which Φ is a full essentially-reflective subcategory. The frA-objects are characterized for which, respectively, ∀ B(frA(A, B) = U (A, B)), and, ∀ B ≠ 0(frA(B, A) = U(B, A)).

In 1962, the author proved that each reduced archimedean f-ring can be represented as an f-ring of continuous extended real-valued function on a locally compact space. The existence of this representation has proved to be quite useful; however, the proof so obscured the definition of the representing functions that deeper applications have remained out of reach. In this paper, we give a new proof of this result; one in which the derivation of the representing functions is more readily accessible. This accessibility is exploited to prove that f-ring homomorphisms on reduced archimedean f-rings are induced by continuous maps between subspaces of their representing spaces, and this leads to further insights into the structure of such homomorphisms.

In a category C an object it G is epicomplete if the only epic monics out of G are isomorphisms, epic or monic meant in the categorical sense of right or left cancellable. For each of the categories Arch: archimedean l-groups with l-homomorphisms, and its companion category W: Arch-objects with distinguished weak unit and unit-preserving l-homomorphisms, (and for the corresponding categories of vector lattices) epicompleteness has been characterized as divisible and conditionally and laterally σ-complete, and it has been shown to be monoreflective.

Three corn hybrids (Pioneer 36F30, Mycogen TMF2450, and Mycogen TMF2404) were compared for yield and quality traits, and lactation performance and apparent digestibility by Holstein cows. The three corn silages were harvested at a target of 33 to 35% dry matter. Before harvest, six corn plants were randomly selected for plant fractionation. Grain-to-stover ratios were 0.92, 0.70, and 0.95 for the 36F30, TMF2450, and TMF2404 corn plants, respectively. Fifty-two multiparous Holstein cows were placed on a 120-d lactation trial after a 21-d covariate diet. Cows were blocked by calving date and randomly assigned within block to one of three dietary treatments, containing approximately 40% (dry matter basis) corn silage. Milk yield, milk components, and dry matter intake did not differ among dietary treatments. In vitro true and neutral detergent fiber digestibilities were numerically higher for TMF2404 than the other corn silage hybrids. Apparent total-tract crude protein and neutral detergent fiber digestibilities, as measured by acid insoluble ash, were higher for TMF2450 than the other two hybrids, but starch digestibility was not different between the corn silage dietary treatments. Although small differences in nutrient content and digestibility existed among corn silage hybrids, inclusion of these leafy hybrids in lactating cow diets at 40% of the dietary dry matter did not have a significant impact on lactation performance of dairy cattle.

The reactions of the methylidene (CH) radical with a variety of methanol isotopomers has been studied using pulsed laser photolysis/laser induced fluorescence, as a function of temperature (298–753 K) and pressure (100–600 Torr helium). The rate coefficient was independent of total pressure and the following rate coefficients were determined: where the errors represent statistical uncertainties at the 1σ level. The reaction can either proceed ia CH insertion into a C–H bond (as for the reaction with methane) or ia an initial complex with subsequent insertion into either the O–H or C–O bonds (as for the reaction with water). The absence of any significant isotope effect indicates that the reaction proceeds ia the latter mechanism, however, the room temperature rate coefficient is an order of magnitude greater than that for the reaction of CH with water. A correlation between the ionization potential of the substrate and rate coefficient is suggested to rationalise experimental observations. Above an ionization potential of approximately 11 eV, there is an inverse correlation between rate coefficient and ionization energy, below an ionization energy of 11 eV, the rate coefficient reaches a plateau of ∽3×10−10 cm3 molecule−1 s−1.

Balloon-borne observations of concentrations of OH, HO2, H2O, and O3 in the middle and upper stratosphere are used to test our understanding of HOx photochemistry. Assuming our photochemical model is complete, the measured [OH] and [HO2] above 38 km (where HOx partitioning is no longer dependent on [NO]) are modeled best by calculations that use a 25% reduction in the ratio of the reaction rate constants for O+HO2 and O+OH as well as either a 25% reduction of the rate constant of OH+HO2 (the primary HOx sink) or a 25% increase in HOx production. All of these changes are consistent with the uncertainties in the recommended rate constants. The kinetic parameters required to explain our observations of [OH] and [HO2] do not lead to a resolution of the long-standing “ozone deficit problem” above 45 km.

Background: Gastric emptying scintiscans are currently used to select reflux patients for added pyloroplasty at the time of fundoplication. The accuracy of this scan selection approach has been assumed. If preoperative scintiscans do not reliably predict postfundoplication gastric emptying, however, the decision to add pyloroplasty to the fundoplication operation may be inappropriate and even harmful. Methods: The authors studied 27 children prospectively before and after gastric fundoplication. Gastric emptying at 60 minutes was measured by double isotopic labeling of liquid ( 111 In) and solid ( 99m Tc) phases of a test meal specifically designed for label fixation. The authors' question involved the accuracy of preoperative gastric scintiscans in predicting postfundoplication delay of gastric emptying (DGE). An evaluation of pyloroplasty as an effective treatment for DGE was not part of the study design. Pyloroplasty was performed as a secondary operation in three of the study children, however, because they persisted with unrelieved symptoms of retching, fullness, and abdominal discomfort. Scintiscan-documented postfundoplication delay in gastric emptying was present in all three patients at 18, 58 and 12 weeks, respectively. Additional scintiscans were performed in these patients after pyloroplasty. Results: Gastric emptying of solids at 60 minutes did not show a significant change after a gastric fundoplication operation, although the trend was in the direction of a decrease (paired t test, P = . 13). Liquid emptying at 60 minutes, however, was significantly increased (paired t test, P = .01). The variation in values between patients was wide, and the correlation between pre- and postoperative study results in the same patient was poor (r 2 = 0.337 for solids and r 2 = 0.116 for liquids). Most unexpectedly, scintiscans after postfundoplication pyloroplasty in the three patients with persistent symptoms showed no improvement in delayed gastric emptying on repeat scintiscan 42 to 117 weeks later. Conclusions: The data suggest that preoperative scintiscan evidence for postfundoplication DGE is probably accurate for solid emptying but not for liquids, at least as measured by the double isotope methodology of our study. Preoperative scintiscans that use a liquid phase label only may be highly misleading for the prediction of postfundoplication DGE. Furthermore, pyloroplasty may not be useful as treatment even when postfundoplication delay in gastric emptying can be accurately anticipated or confirmed. A fundamental motility disorder of the gastric body seems to be more important than muscular resistance at the gastric outlet as a cause for postfundoplication DGE, and the most effective treatment approach remains unclear.

We recently reported that tumor necrosis factor-alpha (TNF-alpha) induction of the synthesis and secretion of transforming growth factor (TGF)-beta 1 by FRTL-5 cells is a thyroid-stimulating hormone (TSH)-dependent and age-dependent process. TNF-alpha is only cytotoxic to aged (> 40 passages) FRTL-5 cells grown in TSH-containing medium, whereas TGF-beta induces programmed cell death (apoptosis) in epithelial cells but not in FRTL-5 cells, which otherwise retain many properties of normal thyroid follicular cells. This cell line is, therefore, a convenient model for studies on the TSH-dependent and age-dependent inhibitory effects of these cytokines on epithelial cell growth, viability, and function. One prominent effect of TNF-alpha (and TGF-beta 1) on FRTL-5 cell function is suppression of iodide uptake, which is markedly stimulated by TSH. In aged FRTL-5 cells, iodide uptake is only about 10% that of young control cells. Na+/K(+)-ATPase activity, which drives iodide uptake by thyroid cells, is inhibited by TNF-alpha and TGF-beta. The following experiments quantitate the effects of TSH, aging, TNF-alpha, and TGF-beta 1 on the expression and activity of Na+/K(+)-ATPase activity in FRTL-5 cells. Young ( 40 passages) FRTL-5 cells were treated with various doses (0-100 ng/ml) of recombinant human TNF-alpha or TGF-beta 1 for various times (0-3 days) with and without 2 U/liter TSH. These treatments reduced the rate-limiting Na+/K(+)-ATPase beta 1 mRNA level and Na+/K(+)-ATPase activity in parallel in a dose-dependent and time-dependent fashion. Aged FRTL-5 cells were more sensitive to the inhibitory effects of TNF-alpha, whereas young cells were more sensitive to the suppressive effects of TGF-beta 1 on the expression and activity of Na+/K(+)-ATPase. We conclude that inhibition of Na+/K(+)-ATPase activity by TNF-alpha and TGF-beta in FRTL-5 cells is differentially affected by aging and that this inhibitory effect can be dissociated from effects on cell viability.

We present laboratory measurements of the absorption cross sections of the ν5 band (540–580 cm−1) of chlorine nitrate made under stratospheric conditions of temperature and pressure. We use the measured cross sections and observed mid-infrared stratospheric emission spectra to retrieve mid-latitude vertical mixing ratio profiles for both day and night in the altitude range 20–34 km, and compare the results with a sunset profile obtained simultaneously from solar absorption measurements of the ν4 Q branch at 780 cm−1. The profiles obtained using these two methods are shown to be in excellent agreement, validating retrievals using the ν4 band. We also find good agreement in this altitude range between the observed day/night ratio and the results of a 1-D photochemical model

We have used hamster insulinoma tumor (HIT) cells, an insulin-secreting tumor cell line, to investigate modulation of the Na/K-ATPase and of the ATP-sensitive K channel (K(ATP)) by the sulfonylurea glyburide. Membrane proteins from cells cultured in RPMI with 11 mM glucose have at least two glyburide receptor populations, as evidenced by high and low binding affinity constants, (K(d) = 0.96 and 91 nM, respectively). In these cells K(ATP) channel activity was blocked by low glyburide concentrations, IC(50) = 5.4 nM. At 12.5 nM glyburide the inhibition developed slowly, tau = 380 s, and caused reduction of channel activity by 75 percent. At higher concentrations, however, inhibition occurred at a fast rate, tau = 42 s at 100 nM, and was almost complete. Na/K-ATPase activity measured enzymatically and electrophysiologically was also suppressed by glyburide, but higher concentrations were needed, IC(50) = 20-40 nM. Inhibition occurred rapidly, tau = 30 s at 50 nM, when maximum, activity was reduced by 40 percent. By contrast, cells cultured in RPMI supplemented with 25 mM glucose exhibit a single receptor population binding glyburide with low affinity, K(d)= 68 nM. In these cells inhibition of the Na/K-ATPase by the sulfonylurea was similar to that observed in cells cultured in 11 mM glucose, but K(ATP) channel inhibition was markedly altered. Inhibition occurred only at high concentrations of glyburide and at a fast rate; maximum inhibition was observed at 100 nM. Based on these data, we propose that glyburide binding to the high affinity site affects primarily K(ATP) channel activity, while interaction with the low affinity site inhibits both Na/K-ATPase and K(ATP) channel activities. The latter observation suggests possible functional interactions between the Na/K-ATPase and the K(ATP) channel.

The Smithsonian Astrophysical Observatory (SAO) maintains a molecular line database (the SAO line database) for analysis of atmospheric spectra in the far i.r. and longer-wave mid i.r., from 10-800 cm -1 . This database combines the best currently available line parameters, including the HITRAN 1.2 molecular database, the JPL submillimeter, millimeter, and microwave spectral line catalog 3 (JPLSMM), and other available measurements and calculations. The current version of the database contains 154.895 lines from H 2 O, CO 2 , O 3 , N 2 O, CO, CH 4 , O 2 (including the 1 Δ state), NO, SO 2 , NO 2 , NH 3 , HNO 3 , OH, HF, HCl, HBr, HI, ClO, OCS, H 2 CO, HOCl, HCN, H 2 O 2 , O( 3 P ), and HO 2 . The database is available in both HITRAN-type 80 character (SAO92) and 100 character (SAO92A) formats. 1. L.S. Rothman, R.R. Gamache, A. Goldman, L.R. Brown, R.A. Toth, H.M. Pickett, R.L. Poynter, J.-M. Flaud, C. Camy-Peyret, A. Barbe, N. Husson, C.P. Rinsland, and M.A.H. Smith, Appl. Opt. 26 , 4058 (1987). 2. L.S. Rothman, R.R. Gamache, R.H. Tipping, C.P. Rinsland, M.A.H. Smith, D. Chris Benner, V. Malathy Devi, J.-M. Flaud, C. Camy-Peyret, A. Perrin, A. Goldman, S.T. Massie, L.R. Brown, and R.A. Toth, JQSRT . 48 , 469 (1992). 3. R.L. Poynter and H.M. Pickett, Submillimeter millimeter and microwave spectral line catalog, Publ. 80-23, revision 2, Jet Propulsion Laboratory, Pasadena, CA (1984).

Holstein calves (n = 110) were used to evaluate the effect of calf starters containing 15, 16.8, 19.6, or 22.4% CP, DM basis (diets A, B, C, and D, respectively), on calf performance from d 4 to 56 of life. Preweaning daily gain tended to increase linearly as protein content of diets increased, averaging .37, .39, .38, and .44 kg/d for diets A, B, C, and D, respectively. After weaning, calves fed diet C gained the most (.86 versus .71, .75, and .79 kg/d for A, B, and D, respectively). Overall BW gains from d 4 to 56 averaged .54, .56, .62, and .61 kg/d for A, B, C, and D, respectively. Throughout the experiment, starter consumption tended to increase as CP content of diet increased. Under these conditions, maximum growth was supported by diet C (19.6% CP); no advantage was gained from higher (22.4%) protein content. Calf growth was moderate when calf starters of lower protein contents (15 or 16.8%) were fed.

Crossbred cows (n=80) resulting from the use of Jersey (JE) semen on their pure Holstein (HO) dams were compared with pure HO cows (n=77) for body weight, body condition score, fertility, and survival during their first 3 lactations. Cows were in 2 research herds of the University of Minnesota and calved from September 2003 to June 2008. The JE × HO crossbred cows had significantly less body weight during the first (-56 kg), second (-67 kg), and third (-82 kg) lactations than pure HO cows. However, JE × HO cows had significantly greater body condition score during the first (2.94 vs. 2.84), second (2.97 vs. 2.84), and third (2.99 vs. 2.87) lactations than pure HO cows. For fertility, JE × HO cows had fewer days to first breeding during the first (-10.6d), second (-8.4d), and third (-12.3d) lactations than pure HO cows. Crossbred cows were not significantly different from pure HO cows for number of services during first lactation; however, JE × HO cows had significantly fewer services (2.2) than pure HO cows (2.7) during the second lactation. Also, JE × HO cows had significantly fewer days open than pure HO cows in the first (-24 d), second (-42 d), and third (-42 d) lactations. For survival, JE × HO cows were not significantly different from pure HO cows for percentage of cows calving a second time; however, a tendency existed for a higher percentage of JE × HO cows (63.8%) than pure HO cows (49.4%) to calve a third time, and a higher percentage of JE × HO cows calved a third time within 28, 34, and 40 mo of first calving than pure HO cows.

cDNA for neutrophil attractant protein-1 (NAP-1, also known as IL-8) was cloned from Con A-stimulated guinea pig spleen cells with human NAP-1 cDNA as a probe. Guinea pig NAP-1 cDNA is composed of 1433 bp with an open reading frame which encodes for a 101-amino-acid protein. Guinea pig NAP-1 had 70% amino acid sequence similarity to human NAP-1, which was much higher than a similarity between human and guinea pig monocyte chemoattractant protein-1 (MCP-1) (56%). Nucleotide sequence similarity within the coding region was 75%. To confirm its biological activity in guinea pig, recombinant guinea pig NAP-1 was expressed in COS-7 cells then purified. N-terminal sequence analysis gave two different N-termini at position 23 (Met) or 24 (Val). The two proteins showed their peak activity for guinea pig neutrophils at the concentration of 1 microgram/ml (10-7 M). Despite its high similarity to human NAP-1, the responsiveness of human neutrophils to guinea pig NAP-1 was minimum. Recombinant guinea pig NAP-1 caused strong neutrophil infiltration after intradermal injection into guinea pig skin. Since guinea pig is classified as a rodent, it was of interest to know whether human NAP-1 cDNA hybridizes to genomic DNA of other rodents such as mouse or rat, in which a NAP-1 homologue has not been found. Under low stringency conditions, human NAP-1 cDNA hybridized to human, rabbit, and guinea pig DNA, but not to mouse or rat DNA. Unlike NAP-1, human MCP-1 cDNA hybridized to genomic DNA of rabbit, guinea pig, mouse, and rat; MCP-1 cDNA have been cloned from these species. The apparent absence of a NAP-1 gene in mouse or rat makes this chemoattractant unique among the members of the protein family to which NAP-1 and MCP-1 belong.

An upper limit is measured for stratospheric HBr from three balloon flights. The observations were made with the FIRS-2 far-infrared Fourier transform spectrometer. The 1sigma upper limits from the 1988, 1989, and 1990 balloon flights are 13 pptv at 35 km, 7 pptv at 32 km, and 3 pptv at 31 km, respectively. Combining all 3 flights, the weighted average 1sigma upper limit for HBr is 4 pptv at 32 km. This value is significantly smaller than the only other previously published spectroscopic value of 20 +/- 7 pptv (2sigma), but is consistent with a theoretical estimate which predicts roughly 0.4 pptv at this altitude.

In a preliminary experiment a single treatment of 2 kg ha−1 glyphosate was found to be as effective as higher rates of application in reducing Cyperus rotundus shoot numbers. Single applications of 11–2 kg ha−1 bromacil and 976 kg ha−1 methyl bromide were compared with multiple applications of 2 kg ha−1glyphosate, 4.5 kg ha−1 2,4‐D, 4 kg ha−1 EPTC, 2.4 kg ha−1 vernolate, 5 kg ha−1 pebulate, 2–9 kg ha−1 amitrole and eight successive rotary hoeings during dry weather, all over a 19‐month period. Most treatments reduced shoot and tuber populations and tuber weights but the most efficient treatments were bromacil, cultivation, glyphosate and 2,4‐D. At the end of the experiment the percentage of tubers with shoots was similar for many treatments but was higher on the thiocarbamate treatments and tended to be lower on the glyphosate treatment. The percentage of dormant or moribund tubers was higher on the glyphosate treatment than on other treatments. The greatest effect of most treatments was on the s...

Pure Holstein calves and Montbeliarde-sired crossbred calves from multiparous Holstein dams were compared for gestation length, calf weight at birth, calving difficulty, and stillbirth in 2 research herds of the University of Minnesota. The Montbeliarde-sired calves from multiparous Holstein dams had significantly longer gestation lengths (283.2 d) than Holstein-sired calves from Holstein dams (278.4 d), and Montbeliarde-sired calves from multiparous Holstein dams had significantly greater calf weight at birth (48.3kg) compared with Holstein-sired calves from Holstein dams (43.3kg). However, calves sired by Montbeliarde bulls were not significantly different from calves sired by Holstein bulls for calving difficulty and stillbirth. In addition, Jersey x Holstein crossbred cows mated to Montbeliarde artificial insemination (AI) bulls were compared with pure Holstein cows mated to Holstein AI bulls for gestation length, calf weight at birth, calving difficulty, and stillbirth at their first 3 calvings. Gestation length was significantly longer for Jersey x Holstein cows bred to Montbeliarde bulls than for pure Holstein cows bred to Holstein bulls at first calving (280.3 versus 277.7 d) and second and third calving (282.2 versus 278.6 d); however, Jeresy x Holstein cows bred to Montbeliarde AI bulls were not significantly different from pure Holstein cows bred to Holstein AI bulls for calf weight at birth, calving difficulty, and stillbirth at the first 3 calvings.

Multiparous Holstein cows at six universities were utilized to examine effects of ruminally protected methionine and lysine on lactational performance. Three hundred and four cows began the study; 259 cows were included in the production analysis. Following a 21-d standardization period, cows received a basal diet of corn silage and ground corn supplemented with one of five dietary treatments, which were supplements of soybean meal or corn gluten meal, the latter with zero and three combinations of protected methionine and lysine (methionine; methionine and lysine; methionine and double (2×) lysine). Treatment effects were evaluated during early, mid, late, and total lactation (22 to 112, 113 to 224, 225 to 280, and 22 to 280 d post-partum respectively). On a DM basis, ratios of forage to concentrate (50:50, 60:40, and 70:30) increased, and dietary CP (16.0, 14.5, and 13.0%) decreased during the three periods of lactation. Amount of amino acid supplementation also decreased (15, 12, and 9 g/d methionine; 20, 16, and 12 g/d lysine; and 40, 32, and 24 g/d 2× lysine) with period of lactation. Actual and least squares means for milk, FCM, and milk protein yields were greater for soybean than for corn gluten meal during early, mid, and total lactation. In addition, these variables responded linearly to lysine in early lactation. Response to lysine was quadratic during mid and total lactation for these variables. Differences in nutrient intake explained production responses to protein sources but not to lysine. Serum amino acid responses primarily reflected differences in dietary protein source and rumen-protected amino acid.

The first unequivocal measurement of hydrogen peroxide in the stratosphere have been made, a concentration profile obtained from a balloon platform using Fourier transform thermal emission spectroscopy in the far infrared. Measurements were made using the 112/cm R-Q5 branch of the rotational-torsional spectrum, with some confirmation from the 94/cm R-Q4 branch. The volume mixing ratio of H2O2 is 1.6 x 10 to the -10th at 38.4 km, decreasing to 0.6 x 10 to the -10th at 23.8 km, with uncertainties of about 16 percent. These measurements are compared to a recent stratospheric model calculation.

Fifty-seven Holstein cows (19 primiparous) were assigned to one of four dietary treatments arranged as a 2 × 2 factorial during d 22 to 150 of lactation to examine the effects of raw or extruded (149°C) soybeans and of rumen-protected methionine and lysine supplements on lactation performance. Dietary DM contained 16.5% CP and consisted of 32.2% alfalfa silage, 5.4% alfalfa pellets, 10.4% corn silage, 38.5% high moisture shelled corn, 11.4% nitrogenous supplements, and 2.1% minerals and vitamins. From d 15 prepartum to d 21 of lactation, all cows were fed a protein supplement of raw and extruded soybeans in a 1:1 ratio. During the experimental period, an average of 18.9 kg of DM were consumed. This contained, for the amino acid-supplemented treatments, 14.2 g each of rumen-protected DL-methionine and L-lysine. Experimental data were adjusted by covariance for means measured during d 4 to 21. Dietary treatments did not affect yield of milk, milk protein or milk casein, DMI, BW and condition, or plasma urea N. Extruded soybeans depressed milk fat percentage. Evaluation of diets in continuous culture fermenters indicated no differences in digestibility of DM and carbohydrates. Ammonia N concentration in the effluent and CP degradation were lower for extruded than for raw soybean diets. Flows of NAN and total amino acids from fermenters did not differ among diets.

The magnetic dipole-allowed spin-rotation lines of O2 potentially can be used for pointing calibration and confirmation of float altitude for far infrared spectra of the stratosphere obtained from balloon platforms. We demonstrate that current deficiencies in the spectroscopic database, particularly the air pressure-broadening coefficients, severely limit the capability of deriving useful pointing calibrations, and that precise pressure-broadening measurements for the transitions actually used in calibration are needed to improve this capability.

Jersey x Holstein crossbreds (JxH; n = 76) were compared with pure Holsteins (n = 73) for 305-d milk, fat, and protein production; conception rate; days open; proportion of cows pregnant within fixed intervals postpartum; and body and udder measurements during first lactation. Cows were housed at 2 research locations of the University of Minnesota and calved from September 2003 to May 2005. The JxH were mated to Montbeliarde sires, and Holstein cows were mated to Holstein sires. Best Prediction was used to determine actual production (milk, fat, and protein) for 305-d lactations with adjustment for age at calving, and records less than 305 d were projected to 305 d. The JxH (274 kg) and pure Holsteins (277 kg) were not significantly different for fat production, but JxH had significantly less milk (7,147 vs. 7,705 kg) and protein (223 vs. 238 kg) production than pure Holsteins. The JxH had significantly fewer days open than pure Holsteins (127 vs. 150 d). Also, a significantly greater proportion of JxH were pregnant at 150 and 180 d postpartum than pure Holsteins (75 vs. 59% and 77 vs. 61%, respectively). The JxH had significantly less body weight (60 kg) at calving, but significantly greater body condition (2.80 vs. 2.71). Furthermore, JxH had significantly less udder clearance from the ground to the bottom of the udder than pure Holsteins (47.7 vs. 54.6 cm), and greater distance between front teats (15.8 vs. 14.0 cm) than pure Holsteins during first lactation.

In previous studies ammonium salts of a mixture of isobutyrate, 2-methylbutyrate, isovalerate, and valerate were fed in a corn silage, corn, corn gluten meal, and urea diet to Holstein cows throughout lactation to define the optimum level of ammonium salts of milk production. The objective of this work was to conduct another dose response study using other forage and protein sources and to determine the effects of decreasing VFA intakes as lactation advanced. The concentrate portion of the diet contained 0, .4, .8, 1.2, or 1.6% ammonium salts of VFA. The forage to concentrate ratio was 50:50, 60:40, and 70:30 for the first, middle, and last third of lactation, respectively. The study was conducted at four university locations using 191 Holstein cows. Feeds used included corn silage, alfalfa silage or hay, corn, soybean meal, minerals, and vitamins. Treatment × location interactions were significant for milk yield during early lactation. During mid- and late lactation, supplemental VFA (3%) improved milk and protein yield. Milk composition was not greatly affected by feeding VFA. In midlactation, cows fed 8% ammonium salts of VFA ate more feed than did controls. Feed efficiencies were similar among groups throughout the experiment. Cows fed VFA tended to gain less BW during lactation than did controls. Health and reproduction were not different among groups.

All immunoglobulin genes contain a conserved octanucleotide promoter element, ATGCAAAT, which has been shown to be required for their normal B-cell-specific transcription. Proteins that bind this octamer have been purified, and cDNAs encoding octamer-binding proteins have been cloned. Some of these proteins (referred to as OTF-2) are lymphoid specific, whereas at least one other, and possibly more (referred to as OTF-1), is found ubiquitously in all cell types. The exact role of these different proteins in directing the tissue-specific expression of immunoglobulin genes is unclear. We have identified two human pre-B-cell lines that contain extremely low levels of OTF-2 yet still express high levels of steady-state immunoglobulin heavy-chain mRNA in vivo and efficiently transcribe an immunoglobulin gene in vitro. Addition of a highly enriched preparation of OTF-1 made from one of these pre-B cells or from HeLa cells specifically stimulated in vitro transcription of an immunoglobulin gene. Furthermore, OFT-1 appeared to have approximately the same transactivation ability as OTF-2 when normalized for binding activity. These results suggest that OTF-1, without OTF-2, is sufficient for transcription of immunoglobulin genes and that OTF-2 alone is not responsible for the B-cell-specific regulation of immunoglobulin gene expression.

We tested the hypothesis that the adenylate cyclase system and Na+, K(+)-ATPase are reciprocally related in rat pancreatic islets. We studied the effect of theophylline, caffeine, and dibutyryl cyclic AMP on Na+, K(+)-ATPase activity in a membrane preparation from collagenase-isolated rat islets. Theophylline, caffeine, or dibutyryl cyclic AMP, in concentrations of 1 mM, all inhibited Na+, K(+)-ATPase activity (44,62, and 43%, respectively). Kinetic analysis indicated that theophylline and dibutyryl cAMP inhibit Na+, K(+)-ATPase by different mechanisms; theophylline decreased Vmax and decreased apparent Km (ATP), whereas dibutyryl cAMP decreased Vmax and increased apparent Km (ATP). Similar inhibition of Na+, K(+)-ATPase by theophylline or dibutyryl cAMP was noted in a particulate fraction from rat kidney and in a purified porcine brain Na+, K(+)-ATPase preparation. The adenylate cyclase system and Na+, K(+)-ATPase may act reciprocally in pancreatic islets and in other tissues. In the beta cell this relationship may be essential in coordinating consumption of ATP in the stimulated, as opposed to the rest, state.

Using a simple photochemical model we derive the mixing ratio profile of ClO in the altitude range 20–38 km from simultaneous measurements of HO2, OH, HOCl, temperature, pressure, and ozone. The measurements were made with the FIRS-2 far-infrared spectrometer during a balloon flight on September 29, 1992. We compare the derived ClO with the ClO profile obtained by the SLS instrument while flying on the same gondola. The good agreement between the two profiles validates our simple model and confirms the relevant rate constants and photolysis cross sections.

[1] Vertical profiles of nitrous oxide and methane at high latitudes (57–72°N; 64–89°S) were observed by the Improved Limb Atmospheric Spectrometer (ILAS) solar occultation sensor aboard Advanced Earth Observing Satellite. These measurements were made continuously from November 1996 through June 1997 with some additional periods in September–October 1996. A validation study of the nitrous oxide and methane data processed with the Version 5.20 ILAS retrieval algorithm is presented in this paper. Comparisons are made with (1) nitrous oxide and methane obtained by the ILAS validation balloon campaigns at Kiruna, Sweden, and at Fairbanks, Alaska, in the Arctic; (2) nitrous oxide and methane by the Photochemistry of Ozone Loss in the Arctic Region in Summer aircraft campaign in the Arctic; (3) nitrous oxide by the ground-based spectroscopic measurements and by the aircraft-based remote sensing measurements in the Arctic; and (4) methane by satellite measurements of the Version 19 Halogen Occultation Experiment in the Arctic and Antarctic. Comparisons of ILAS nitrous oxide and methane with Upper Atmosphere Research Satellite Reference Atmosphere data are also made. The results of the comparisons and additional ILAS internal consistency analyses are as follows: (1) the uncertainty of ILAS nitrous oxide is better than 10% over 10–30 km in altitude, and is larger than 50% over 30–40 km, which is comparable to the expected total errors of the ILAS measurements; (2) the uncertainty of ILAS methane is better than 10% over 10–50 km, except for 15–30 km in winter with positive biases exceeding 20%, which is smaller than or comparable to the expected total errors of the ILAS measurements (the quality of ILAS methane in the polar lower stratosphere is better in summer than in winter). In summary, the characteristics of ILAS measurements, i.e., high sampling frequency in polar latitudes with high vertical resolution, along with the good quality of ILAS Version 5.20 nitrous oxide for 10–40 km and the good quality of ILAS Version 5.20 methane for 10–50 km except for 15–30 km in winter, make the ILAS nitrous oxide and methane data set valuable for scientific study of various polar stratospheric phenomena.

[1] Vertical profiles of water vapor concentration at high latitudes (57-72 degreesN; 64-89 degreesS) were observed by the Improved Limb Atmospheric Spectrometer (ILAS) solar occultation sensor aboard the Advanced Earth Observing Satellite (ADEOS). These measurements were made continuously from November 1996 through June 1997 with some additional periods in September to October 1996. A validation study of the water vapor data processed with the version 5.20 ILAS retrieval algorithm is presented in this paper. Uncertainty and general characteristics of the ILAS water vapor measurements are briefly reviewed. Comparisons are made with data obtained by (1) the ILAS validation balloon campaigns at Kiruna, Sweden and at Fairbanks, Alaska; (2) the aircraft measurements under the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaign; and (3) available satellite measurements of the version 19 Halogen Occultation Experiment (HALOE) and the version 6 Stratospheric Aerosol and Gas Experiment II (SAGE II). The agreement between ILAS water vapor and all independent reliable correlative measurements in the altitude region of 15-60 km is better than 10% for the majority of cases and better than 20% for all comparisons, with the exception of some isolated cases detailed in this paper. Climatological comparisons of ILAS data with Upper Atmosphere Research Satellite (UARS) climatology and HALOE data show the overall consistency of ILAS water vapor data considering the known features of atmospheric circulation. The characteristics of ILAS measurements, i.e., high sampling frequency in polar latitudes with high vertical resolution along with the good data quality, make the ILAS water vapor data set valuable for various polar stratospheric research applications.

[1] Comparisons of remote sensing stratospheric mixing ratio profiles for O3, H2O, N2O, HNO3, and NO2 are shown between data (version 5.2) obtained by the Improved Limb Atmospheric Spectrometer (ILAS) on board the Japanese Advanced Earth Observing Satellite (ADEOS) and the Smithsonian Astrophysical Observatory far-infrared spectrometer (FIRS)-2 balloon-borne spectrometer from a flight on 30 April 1997 originating in Fairbanks, Alaska. Submillimeter wave remote sensing and UV in situ observations of mixing ratios of O3 from Jet Propulsion Laboratory (JPL) instruments obtained on board the same balloon gondola are also used for comparison with ILAS mixing ratios of O3. The remote sensing balloon observations occurred roughly 5° latitude, and the in situ 2° latitude, north of the nearest ILAS observations and were taken between 0700 and 1300 local solar time (LST), while the ILAS data were taken at the previous local sunset (near 2100 LST). Back trajectories from the locations and times of balloon data sets to the prior local sunset were within 2° latitude and 10° longitude of the nearest ILAS occultation; the validation therefore effectively occurred in very nearly the same air mass as was observed with ILAS, and well within a 1-day time interval. The mixing ratio profiles of all of the compared molecules (O3, HNO3, N2O, H2O, and NO2) agree to within the combined uncertainties with only minor systematic offsets.

International audience; Vertical profiles of ozone concentration in the high latitudes were observed by the Improved Limb Atmospheric Spectrometer (ILAS) aboard the Advanced Earth Observing Satellite (ADEOS) from November 1996 to June 1997. The ozone data obtained by the version 5.20 ILAS retrieval algorithm are compared with those obtained by the version 19 Halogen Occultation Experiment (HALOE), the version 6 Stratospheric Aerosol and Gas Experiment (SAGE) II, and the version 6 Polar Ozone and Aerosol Measurement (POAM) II retrieval algorithms. The ILAS data are also compared with ozone data measured by ozonesondes, instruments on board balloons or an aircraft, and ground-based instruments. The ILAS ozone data generally agree with its correlative data between 11 and 64 km with some exceptions. Quantitatively, the median value of the relative difference (absolute difference divided by its mean value) for these comparisons was within ±10%. Relative differences (18%) exceeding the combined measurement errors were found around 45–55 km altitude from comparisons with the HALOE and SAGE II data in January 1997 in the Southern Hemisphere (SH). Larger relative differences (around 50%) were also found below 15 km from comparisons with the HALOE and POAM II data in November 1996 in the SH, but these absolute differences were 0.10–0.16 ppmv as the median value. The ozone data processed by the version 5.20 were improved compared to the former version 3.10, which is available to the general public. The version 5.20 ozone data can be used for scientific analysis purposes based on the accuracy of the data in comparison with these other instruments.

The transcription factor E2F-1, a downstream regulator of the p16-cyclinD-Rb pathway, is required for cell cycle progression. Evidence shows that overexpression of E2F-1 can either promote or inhibit development of tumors, depending on tissue or experimental conditions. To study whether the E2F-1 gene plays a role in tumor progression, the expression of E2F-1 protein was evaluated in 10 human head and neck squamous cell carcinoma cell lines using Western blot analysis. In addition, the invasive ability of these cell lines was determined by evaluating the penetration of cell lines into the tracheal wall in an in vivo invasion assay using deepithelialized tracheas transplanted into the s.c. tissue of Scid mice. This study showed that the aggressive cell lines had higher expression of E2F-1 than the less invasive cell lines. To evaluate the hypothesis that E2F-1 enhances invasiveness, we selected two cell lines, SCC9 and SCC12, for a gene transfer experiment. These cell lines exhibited low invasive ability with low expression of E2F-1. Two stable clones with overexpression of transfected E2F-1 gene and two clones with their respective vector-alone control were selected from each cell line for in vivo invasion evaluation. The clones containing the transfected E2F-1 gene had significantly higher invasive ability than their respective vector-alone clones. Flow cytometry showed that parental, transfected E2F-1, and vector-alone cells had a similar proliferation pattern under normal culture conditions. Nevertheless, transfected E2F-1 cells exhibited a higher portion of cells in S phase than the control cells after serum-starvation and refeeding. The results indicated that overexpression of E2F-1 plays a positive role in cell cycle reentry from quiescence and is associated with increased in vivo invasiveness.

Four novel anti-HIV macrocyclic peptides containing 28-31 amino acid residues, named cycloviolins A-D, have been isolated from the hitherto unstudied tropical plant Leonia cymosa. Their primary structure, including amino acid composition and sequence, was determined by a combination of MALDI-TOF and FAB MS and by enzymatic digestion of reduced derivatives, followed by Edman degradation and mass analyses. All of the cycloviolins contain six cysteines, which are present as three intramolecular disulfide bridges. Intriguingly, cycloviolins A-D showed high degrees of sequence homology to the known cyclopsychotride A and circulins A and B from the Rubiaceae family but much less homology to the varv peptides from Viola, a member of the same family (Violaceae).

Cancer cells often contain mutations that lead to the loss of retinoblastoma tumor suppressor (Rb) function and the activation of E2F-dependent transcription. As a result, proliferation is deregulated, and sensitivity to apoptotic stimuli is increased. In cell culture studies, the transcription factor E2F1 has been shown to be equally adept at inducing proliferation and apoptosis. Several groups using mouse models have been examining how these E2F1-regulated processes impact the development of cancer. The conclusion from these studies is that E2F1 can function as both oncogene and tumor suppressor gene and that both positive and negative effects on tumorigenesis can be observed whether E2F1 is absent or overexpressed. These findings are discussed in the context of a model in which pathways controlling cell-cycle progression and apoptosis are intimately linked.

HIV-1 nucleocapsid protein (NCp7) is a double zinc-fingered protein that has been traditionally implicated in viral RNA recognition and packaging, in addition to its tight association with genomic RNA and tRNA primer within the virion nucleocapsid. The availability of large quantities of viral or recombinant wild-type NCp7 and mutant p7 has made possible the assignment of the different roles that structural motifs within the protein play during RNA binding. At low ionic strength binding to the homopolymeric fluorescent RNA, poly(epsilonA), is electrostatically driven and four sodium ions are displaced. Arg7 in the flanking N-terminal region, Lys20 and Lys26 in the first zinc finger and one positively charged residue (attributed to Lys41) in the second zinc finger are involved in electrostatic contacts with RNA. The p7 zinc fingers do not function independently but concomitantly. The first zinc finger (both isolated or in the context of the full-length protein) has a more prominent electrostatic interaction than the second one. The second zinc finger dominates the non-electrostatic stabilization of the binding to RNA due to stacking of its Trp residue with nucleic acid bases. Mutations in the highly conserved retroviral Zn-coordinating residues (CCHC) to steroid hormone receptor (CCCC) or transcription factor (CCHH) metal cluster types do not affect RNA binding. In spite of the limited impact in RNA binding affinity in vitro or RNA packaging in vivo that such mutations or structural alterations impart, they impair or abolish virus infectivity. It is likely that such an effect stems from the involvement of NCp7 in crucial steps of the virus life cycle other than RNA binding.

Several regulators of E2F transcriptional activity, including the retinoblastoma tumor suppressor (Rb) protein, p16Ink4a, cyclin D1, and cyclin-dependent kinase 4, have been shown to be targets for genetic alterations that underlie the development of human cancers. Deregulation of E2F transcription factors as a result of these genetic alterations is believed to contribute to tumor development. This hypothesis is supported by the finding that at least some members of the E2F gene family can contribute to oncogenic transformation when overexpressed. Each E2F family member can dimerize with DP proteins, bind consensus E2F sites, and activate transcription. Several pieces of evidence suggest, however, that the various E2F species have unique functions in regulating transcription. We compared the abilities of E2F1, E2F4, and E2F5 to activate transcription from a variety of gene promoters and found that in all cases E2F1 was the most potent activator, followed by E2F4 and then by E2F5. Construction of chimeric proteins between E2F1 and E2F4 demonstrated that either the carboxy terminus or the amino terminus of E2F1 could make E2F4 a more potent activator. In contrast, neither the carboxy terminus nor the amino terminus of E2F1 could significantly increase the activity of E2F5. We found that, consistent with a role for E2F5 in transcriptional repression, E2F5's binding partner p130, like Rb, could also actively repress transcription when directly bound to a target promoter.