Evaluation of university library impact on students’ academic success

U radu se iznosi teorijski okvir vrednovanja knjižnica, a posebno se govori o mogućnostima istraživanja utjecaja zbirki i usluga sveučilišnih knjižnica na akademski uspjeh studenata. Ukazuje se na terminološke probleme vezane uz vrednovanje knjižnica, o važnosti vrednovanja za poslovanje knjižnica, o knjižničnoj statistici, a posebno o mjerenju utjecaja knjižničnih zbirki i usluga na korisnike. U Hrvatskoj se do sada nisu provodila istraživanja utjecaja sveučilišnih knjižnica na korisnike, a istraživanja vezanih uz utjecaj knjižnice na obrazovanje studenata jako je malo i u svijetu. Razlog tome je činjenica da je utjecaje relativno teško izmjeriti, no oni su veoma važni pokazatelji uspješnosti poslovanja određene akademske knjižnice.The paper gives a theoretical framework for library evaluation, and indicates possible effects the library collections and services might have on students’ academic achievement. The paper discusses terminological problems, the importance of evaluation for library performance, library statistics, and focuses on the measurement of impact of library collections and services on their users. So far, there has been no research in Croatia about the impact of university libraries on student academic achievement, and the studies that deal with this topic are rare even around the world. The reason for this lies in the fact that the outcomes are very difficult to measure, and are therefore avoided in measurements. However, they represent extremely important indicators of university library impact on students’ academic performance

Respective abilities of mutant β clamp proteins to support DNA damage-induced mutagenesis.

<p>Frequencies of (<b>A</b>) UV- or (<b>B</b>) MMS-induced mutagenesis were measured as described in <i>Material and Methods</i> using strains RW118 (WT; <i>dnaN⁺ umuD⁺C⁺</i>), RW120 (ΔumuD; <i>dnaN⁺</i> Δ<i>umuDC595</i>::<i>cat</i>), or the <i>umuD⁺C⁺</i> plasmid shuffle strains MS202 (β⁺), MS203 (β^Q61K), MS204 (β^S107L), MS205 (β^G157S), MS206 (β^V170M), MS207 (β^E202K) and MS208 (β^M204K), as indicated. Results represent the average of 5 independent determinations. Error bars represent one standard deviation. <i>P</i>-values ≤0.05 are indicated, and were calculated using the Student's <i>t</i>-test.</p

Mutant clamps confer resistance to HU.

<p>HU sensitivity was measured as described in <i>Material and Methods</i> using plasmid shuffle strains MS202 (β⁺), MS203 (β^Q61K), MS204 (β^S107L), MS205 (β^G157S), MS206 (β^V170M), MS207 (β^E202K) and MS208 (β^M204K). This experiment was performed at least twice; results from one representative experiment are shown.</p

Ability of mutant β clamp proteins to support viability of <i>E. coli</i>.

a<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone-0098791-t001" target="_blank">Table 1</a> for a description of the plasmids.</p>b<p>Amino acid substitutions are indicated in superscript (<i>e.g</i>., Q61K represents a lysine substitution of residue Q61).</p>c<p>Amp^R CFU/Cam^R CFU is a direct measure of the fraction of Cam^R pACM clones bearing the Amp^R pAMP<i>dnaN⁺</i> plasmid. It was determined by selecting at random colonies that had been passaged for ∼100 generations on LB-Cam plates and patching them onto LB-Amp and LB-Cam plates. Ratios (Amp^R CFU/Cam^R CFU) observed for each plasmid are shown, while the % frequency is shown in parentheses. At least 1 representative clone for each Cam^R and Amp^S strain identified was further characterized to verify the presence of the chromosomal <i>dnaN^–1FS</i> allele using diagnostic PCR and <i>Xho</i>I restriction, as well as nucleotide sequence of the plasmid-encoded <i>dnaN</i> allele.</p>d<p>Viability refers to the ability of the Cam^R transforming plasmid to support growth of <i>E. coli</i> in the absence of pAMP<i>dnaN⁺</i>. Symbols are as follows: –, plasmid is unable to support viability of <i>E. coli</i>, meaning 100% of the CFUs are resistant to both Amp and Cam after ∼100 generations of growth under selection for Cam^R; +, plasmid is able to support viability of <i>E. coli</i>.</p>e<p>Plasmid pACMβ5A expresses the β^148–152 mutant, which contains alanines in place of residues H148-R152 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone.0098791-Sutton2" target="_blank">[10]</a>. This mutation failed to support <i>E. coli</i> viability when crossed onto the bacterial chromosome <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone.0098791-Heltzel1" target="_blank">[6]</a>, and serves as an additional negative control for the plasmid shuffle assay.</p

Effect of overexpression of the different <i>umuDC</i> gene products on growth of AB1157.

<p>Average colony diameters of pGB2 (control), pGY9739 (UmuD₂C) or pGY9738 (UmuD'₂C) transformants of strain AB1157 following growth at either 30°C or 42°C, as noted, are shown. No colonies were observed for the AB1157 pGY9739 transformant. Experiments were performed at least twice. Error bars represent one standard deviation. <i>P</i>-values ≤0.05 are indicated, and were calculated using the Student's <i>t</i>-test.</p

Effect of overexpression of different mutant clamps on growth of AB1157.

<p>(<b>A</b>) Shown are representative images of LB agar plates of AB1157 transformants following 18 hrs of growth at 30°C using the indicated plasmids. (<b>B</b>) Colonies were measured as described in <i>Materials and Methods</i>, and their respective sizes are represented relative to that observed for the AB1157(pBR322) control strain, which was set equal to 1.0. The asterisk (<b>*</b>) indicates strains whose average colony diameter was below the measurement limit of 0.2 mm. Experiments were performed at least twice. Error bars represent one standard deviation. <i>P</i>-values ≤0.05 are indicated, and were calculated using the Student's <i>t</i>-test.</p

Design of the <i>dnaN^–1FS</i> allele and its use in the plasmid shuffle assay.

<p>(<b>A</b>) Genomic structure of the <i>dnaA-dnaN-recF</i> operon. Genes in grey are essential for cell viability, while those in white are non-essential. Blackened triangles represent approximate positions of confirmed promoters, based on EcoGene 3.0 (<a href="http://www.ecogene.org" target="_blank">http://www.ecogene.org</a>). Gross structure of the <i>dnaA–dnaN^–1FS–tet–recF</i> cassette is depicted below. Δ<i>Xho</i>I represents the approximate location of the –1 frameshift mutation present within the <i>dnaN</i>^{–<i>1FS</i>} allele. The <i>dnaN</i>^{–<i>1FS</i>} allele is predicted to express a protein of 134 residues: the N-terminal 49 residues are identical to the wild-type β clamp protein (white), while the C-terminal 85 residues are distinct and result from the −1 frameshift mutation (light grey). The majority of the <i>dnaN^–1FS</i> allele is not translated (black), due to the premature stop codon at position 135 resulting from the altered reading frame. Relative positions of oligonucleotide primer pairs (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone-0098791-t001" target="_blank">Table 1</a>) used for diagnostic PCR amplification or nucleotide sequence analysis are shown. Expected sizes (in bp) for products of PCR amplified fragments using the noted primer pairs are indicated. (<b>B</b>) The MS201 strain contains <i>dnaN^–1FS</i> allele on its chromosome, and bears the Amp^R plasmid pAMP<i>dnaN⁺</i>, which expresses physiological levels of wild type β clamp that supports viability. After transforming strain MS201 to Cam^R with pACM/pACM-derivatives containing the indicated <i>dnaN</i> allele, representative pAMP<i>dnaN⁺</i> and pACM (or pACM derivative) double transformants are passaged for ∼100 generations before patching onto LB-Amp and LB-Cam plates to score for pAMP<i>dnaN⁺</i> retention (<i>i.e.</i>, Amp^R). If the mutant clamp expressed from the pACM plasmid can support viability, pAMP<i>dnaN⁺</i> is lost, and cells display an Amp^S Cam^R phenotype. If the mutant clamp expressed from pACM cannot support viability, the wild type clamp-expressing plasmid pAMP<i>dnaN⁺</i> is retained, and cells display an Amp^R Cam^R phenotype. As controls for strains that readily lost pAMP<i>dnaN⁺</i>, we verified the nucleotide sequence of the plasmid encoded <i>dnaN</i> allele, as well as the structure of the chromosomal <i>dnaN^–1FS</i> allele (see <i>Materials and Methods</i>).</p

Summary of the positions of β clamp mutations.

<p>Shown are (<b>A</b>) front and (<b>B</b>) side views of the β clamp on DNA (PDB: 3BEP). Amino acid positions bearing substitutions that failed to confer cold sensitive growth when co-overexpressed with Pol V are represented as red sticks in the green clamp protomer. The two residues mutated in the <i>dnaN159</i>(Ts) allele (β159; G66→E and G174→A) are indicated as red spacefill in the blue clamp protomer. Loops 1–3 of clamp are higlighted in orange in the blue clamp protomer; loops 1 and 2 contacted DNA in the crystal <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone.0098791-Georgescu1" target="_blank">[5]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098791#pone.0098791-Heltzel1" target="_blank">[6]</a>. The grey ovals represent the approximate location of the hydrophobic cleft present in each clamp protomer that contacts the CBM located in most, if not all clamp partners. This image was generated using PyMOL v1.5.0.2.</p

<i>E. coli</i> strains, plasmid DNAs and oligonucleotides used in this study.

a<p>The complete annotated genotype for strain RW118 is: <i>rpsL31 xyl-5 mtl-1 galK2 lacY1 tsx-33 supE44 thi-1 hisG4(Oc) argE3(Oc) araD139 thr-1 Δ(gpt-proA)62 sulA211.</i></p>b<p>CGSC: <i>E. coli</i> Genetic Stock Center, Yale University, New Haven, CT 06520, USA.</p>c<p>These strains were generated by plasmid shuffle; see <i>Material and Methods</i> for a detailed description of the <i>dnaN</i> plasmid shuffle assay. For strains MS202-MS208, the sequence of each plasmid encoded <i>dnaN</i> allele was verified by automated nucleotide sequence analysis, and the –1 frameshift mutation in the <i>dnaN^–1FS</i> allele was confirmed by diagnostic PCR and <i>Xho</i>I restriction analysis.</p>d<p>The complete annotated genotype for strain AB1157 is: <i>xyl-5 mtl-1 galK2 rpsL31 kdgK51 lacY1 tsx-33 supE44 thi-1 leuB6 hisG4(Oc) mgl-51 argE3(Oc) rfbD1 proA2 ara-14 thr-1 qsr-9 qin-111.</i></p>e<p>The complete annotated genotype for strain MG1655 is: <i>ilvG rfb-50 rph-1</i>.</p>f<p>The sequence corresponding to the <i>Xho</i>I restriction endonuclease site (CTCGAG) within the <i>dnaN</i>^{–<i>1FS</i>} allele, which contains a C→T substitution and −1 dG frameshift (CTTAG), is shown in lower case italics.</p

OUMC29531

Acaenoplax hayae posterior VAMXL file for specimen OUM C.2953