87 Probiotic Supplementation Improves Lamb Performance When Transitioning to High Concentrate Diets

Lamb ruminal function is integral to their health and performance. To enhance growth post-weaning, lambs are often fed a high concentrate diet. While this strategy is common, issues can arise with ruminal acidosis from excess grain consumption, including reduced weight gain and mortality. We hypothesized that administering probiotics orally prior to the transition to concentrate feeds would improve lamb performance. To assess this, finewool lambs (n = 103; males: n = 47, females: n = 56) were weaned from their dams at approximately 100 days of age at an average body weight (BW) of 25.8 ±0.2 kg and placed in a feedlot. Lambs were randomly assigned to treatments, balanced by sex, of 0g, 5g, or 10g of an orally administered probiotic paste (ProBios, Menomonie, WI) containing live lactate producing bacteria. Treatments were administered upon arrival at the feedlot. Lambs were limit fed for 9 days and gradually transitioned to ad libitum access to a high concentrate ration. At 6 weekly intervals, BW, average daily gain (ADG) and blood plasma were collected. Mixed model analysis, with initial weight as a covariate, revealed that lambs receiving 10g of supplement were significantly heavier (P = 0.01) than 5g and 0g treated lambs (30.3±0.2 kg versus 29.9±0.2 kg and 29.6±0.2 kg). ADG was analyzed with fixed effects of treatment and sex. Analysis revealed that ADG tended to be greater for lambs receiving 10g treatment than those receiving 5g or 0g (P = 0.07). Four incidences of mortality were recorded; however there were no significant treatment or sex effects on lamb mortality. These data suggest that probiotic supplementation may be an effective strategy to decrease detrimental effects of diet transition on feeder lambs and may increase lamb performance while transitioning to a high concentrate diet.

278 Replacing cottonseed meal and sorghum grain with corn dried distillers grains with solubles in lamb feedlot diets: volatile compounds from cooked lamb chops

Dorper ram lambs (n = 46) were fed diets replacing cottonseed meal (CSM) and sorghum grain with dried distillers grains with solubles (DDGS). Lambs were fed with ad libitum access to 70.9% concentrate diets for 61 d in individual pens. The positive control diet (CNTL) contained CSM, sorghum grain, and other concentrates, but no DDGS. The four treatment diets were similar to CNTL, but did not contain CSM. Corn DDGS replaced 0%, 33%, 66% or 100% of the sorghum grain in the treatment diets. Lambs fed CNTL were contrasted to those fed 0% DDGS and linear and quadratic effects were evaluated within the four treatment diets. At 48-h postmortem, the longissimus muscle was removed from the carcass, frozen, thawed, cooked, and volatiles were collected using SPME/GC/MS. One volatile, 3-methyl,1-butanol was greater (P = 0.03) in CNTL, while 0DDGS had effectively no volatile present. For linear effects, 1-heptanol (fruity aroma) and 2-pentyl furan (caramel aroma) tended to increase linearly (P = 0.06 and 0.05, respectively), while 2-butanone tended to decrease linearly (P = 0.06; fruity-green aroma) in chops as DDGS increased in the diet. Additionally, 2-heptanone (P = 0.02; banana aroma) and heptanol (P = 0.03; woody aroma) both increased linearly in chops as DDGS increased in the diet. In the quadratic effects, decanoic acid (ethyl ester; grape aroma) tended to decrease quadratically (P = 0.07), while 2-butanone, methyl pyrazine (meaty, roasted aroma), and 2-ethyl-5-methyl pyrazine (coffee, nutty aroma) tended to increase quadratically (P = 0.05, 0.09, and 0.08, respectively) in chops with an increase in DDGS. The volatiles 2,5-dimethyl pyrazine (musty, cocoa aroma) and 2,3-octanedione (warmed-over aroma) both increased quadratically (P < 0.05) in chops as DDGS increased in the diet. Except for 2,3-octanedione, volatile aroma compounds were enhanced when DDGS replaced CSM and sorghum grain in lamb feedlot diets.

275 Replacing cottonseed meal and sorghum grain with corn dried distillers grains with solubles in lamb feedlot diets: carcass characteristics and sensory panel traits

Carcass and sensory panel traits were evaluated in Dorper ram lambs (n = 46) fed feedlot diets where cottonseed meal (CSM) and sorghum grain were replaced with dried distillers grains with solubles (DDGS). In a randomized design study, lambs were individually fed ad libitum 70.9% concentrate diets for 61 d in individual pens. The positive control diet (CNTL) contained CSM, sorghum grain, and other concentrates, but no DDGS. Four treatment diets were similar to CNTL, but did not contain CSM. Corn DDGS replaced 0% (0DDGS), 33% (33DDGS), 66% (66DDGS) or 100% (100DDGS) of the sorghum grain in the treatment diets. Lambs fed CNTL were contrasted to those fed 0DDGS and linear and quadratic effects were evaluated within the four treatment diets. At 48-h postmortem, the longissimus thoracis was removed from the carcass, frozen, thawed, cooked, and evaluated by a trained sensory panel. Lambs fed CNTL had greater (P ≤ 0.03) hot carcass weight (HCW) and ribeye area (REA) than lambs fed 0DDGS. As DDGS incrementally replaced sorghum grain, HCW and flank fat quadratically increased (P ≤ .05), marbling linearly decreased (P = 0.03), ribeye area tended to linearly increase (P = 0.06), and skeletal maturity tended to linearly decrease (P = 0.06). No differences in sensory characteristics were observed (P ≥ 0.06) between lambs fed CNTL or 0DDGS. As DDGS incrementally replaced sorghum grain, juiciness linearly increased (P = 0.03), cook loss quadratically increased (P = 0.05), lamb flavor identity tended to quadratically increase (P = 0.09) and certain flavor attributes quadratically increased (brown, roasted, umami; P ≤ 0.03), quadratically decreased (metallic; P = 0.004), or linearly increased (bloody; P = 0.003). Results indicated that carcass and sensory characteristics are not negatively affected (some are enhanced) when DDGS replaces CSM and sorghum grain in Dorper lamb feedlot diets.

PSIV-B-32 Late-Breaking: Consistency of industry related terminology utilized in assessment questions across instructors of an introductory animal science course

The consistency of instruction between various sections of introductory courses is a concern in higher education, along with properly preparing students to enter careers in industry. The study was conducted at Texas A&M University, using an introductory course, General Animal Science, within the Department of Animal Science. This course was chosen due to the utilization of specific animal science industry related terminology within the course content in support of learning outcomes. The study was a quantitative nonexperimental research method that was conducted over a single semester in 2018. General Animal Science is a large-scale course that contains multiple sections, and this study evaluated assessments created by individual faculty members who instructed different sections, Section A and Section B. These sections were selected as they were composed of both animal science majors and non-majors. Section A had a significantly higher (P < 0.001) number of majors versus non-majors than Section B. Assessment questions were collected from all examinations and quizzes distributed throughout the semester and were compiled into a single document for coding. These specific terms were chosen from literature to provide a benchmark for a potential relationship between student performance on questions containing industry related terminology as opposed to those that do not. Comparing the use of specific industry coded terminology in assessment questions yielded no significant difference (P < 0.05) between the two instructors or sections. These findings demonstrate consistent use of benchmarked industry related terminology in assessment questions across multiple sections, irrespective of individual instructor or student major. This provides a necessary foundation for future analysis of student performance.

Endometrial Glands Are Required for Preimplantation Conceptus Elongation and Survival1

Endometrial glands secrete molecules hypothesized to support conceptus growth and development. In sheep, endometrial gland morphogenesis occurs postnatally and can be epigenetically ablated by neonatal progestin exposure. The resulting stable adult uterine gland knockout (UGKO) phenotype was used here to test the hypothesis that endometrial glands are required for successful pregnancy. Mature UGKO ewes were bred repeatedly to fertile rams, but no pregnancies were detected by ultrasound on Day 25. Day 7 blastocysts from normal superovulated ewes were then transferred synchronously into Day 7 control or UGKO ewes. Ultrasonography on Days 25-65 postmating indicated that pregnancy was established in control, but not in UGKO ewes. To examine early uterine-embryo interactions, four control and eight UGKO ewes were bred to fertile rams. On Day 14, their uteri were flushed. The uterus of each control ewe contained two filamentous conceptuses of normal length. Uteri from four UGKO ewes contained no conceptus. Uteri of three UGKO ewes contained a single severely growth-retarded tubular conceptus, whereas the remaining ewe contained a single filamentous conceptus. Histological analyses of these uteri revealed that endometrial gland density was directly related to conceptus survival and developmental state. Day 14 UGKO uteri that were devoid of endometrial glands did not support normal conceptus development and contained either no conceptuses or growth-retarded tubular conceptuses. The Day 14 UGKO uterus with moderate gland development contained a filamentous conceptus. Collectively, these results demonstrate that endometrial glands and, by inference, their secretions are required for periimplantation conceptus survival and development.

Ovine uterine gland knock-out model: effects of gland ablation on the estrous cycle

Ovine endometrial gland development is a postnatal event that can be inhibited epigenetically by chronic exposure of ewe lambs to a synthetic progestin from birth to puberty. As adults, these neonatally progestin-treated ewes lack endometrial glands and display a uterine gland knockout (UGKO) phenotype that is useful as a model for study of endometrial function. Here, objectives were to determine: 1) length of progestin exposure necessary from birth to produce the UGKO phenotype in ewes; 2) if UGKO ewes display normal estrous cycles; and 3) if UGKO ewes could establish and/or maintain pregnancy. Ewe lambs (n = 22) received a Norgestomet (Nor) implant at birth and every two weeks thereafter for 8 (Group I), 16 (Group II), or 32 (Groups III and IV) weeks. Control ewe lambs (n = 13) received no Nor treatment (Groups V and VI). Ewes in Groups I, II, III, and VI were hemihysterectomized (Hhx) at 16 weeks of age. After puberty, the remaining uterine horn in Hhx ewes was removed on either Day 9 or 15 of the estrous cycle (Day 0 = estrus). Histological analyses of uteri indicated that progestin exposure for 8, 16, or 32 weeks prevented endometrial adenogenesis and produced the UGKO phenotype in adult ewes. Three endometrial phenotypes were consistently observed in Nor-treated ewes: 1) no glands, 2) slight glandular invaginations into the stroma, and 3) limited numbers of cyst- or gland-like structures in the stroma. Overall patterns of uterine progesterone, estrogen, and oxytocin receptor expression were not different in uteri from adult cyclic control and UGKO ewes. However, receptor expression was variegated in the ruffled luminal epithelium of uteri from UGKO ewes. Intact UGKO ewes displayed altered estrous cycles with interestrous intervals of 17 to 43 days, and they responded to exogenous prostaglandin F(2 approximately ) (PGF) with luteolysis and behavioral estrus. During the estrous cycle, plasma concentrations of progesterone in intact control and UGKO ewes were not different during metestrus and diestrus, but levels did not decline in many UGKO ewes during late diestrus. Peak peripheral plasma concentrations of PGF metabolite, in response to an oxytocin challenge on Day 15, were threefold lower in UGKO compared to control ewes. Intact UGKO ewes bred repeatedly to intact rams did not display evidence of pregnancy based on results of ultrasound. Collectively, results indicate that 1) transient, progestin-induced disruption of ovine uterine development from birth alters both structural and functional integrity of the adult endometrium; 2) normal adult endometrial integrity, including uterine glands, is required to insure a luteolytic pattern of PGF production; and 3) the UGKO phenotype, characterized by the absence of endometrial glands and a compact, disorganized endometrial stroma, limits or inhibits the capacity of uterine tissues to support the establishment and/or maintenance of pregnancy.

Comparison of naturally acquired parasite burdens among Florida native, Rambouillet and crossbreed ewes

The response to natural infection by gastrointestinal nematodes was evaluated in three groups of lambing mature ewes: 16 Florida Native; 21 Rambouillet; and 18 1/2 Florida Native x1/2 Rambouillet (F1 generation). Fecal egg counts (FEC), packed cell volume (PCV) and plasma protein levels were determined periodically through a one-year period. The highest FEC was recorded in Rambouillet ewes, with most of the means higher than 1000 eggs per gram (EPG). Florida Native and F1 ewes showed similar trends in FEC, with most of the means below 500 EPG. The highest mean PCV values were recorded in Florida Native ewes, followed in decreasing order by F1 and Rambouillet ewes. F1 ewes showed the lowest plasma protein levels and Florida Natives the highest. Fecal cultures revealed the highest percentages of Haemonchus larvae in Rambouillet ewes (>64%) and the lowest percentages in Florida Native ewes. Florida Native and F1 ewes were more resistant to gastrointestinal nematode infections than were Rambouillet ewes. High negative correlation coefficients between FEC x PCV and FEC x plasma protein levels coincided with peaks in mean FEC of Rambouillet (May and July), Florida Native and F1 ewes (October). This study showed that crossbreeding Rambouillet and Florida Native sheep resulted in the production of F1 ewes resistant against gastrointestinal nematode infections.

Differential effects of intrauterine and subcutaneous administration of recombinant ovine interferon tau on the endometrium of cyclic ewes

Interferon tau (IFNtau) is the antiluteolytic signal produced by the conceptus of ruminants. Intrauterine administration of recombinant ovine IFNtau suppresses expression of endometrial estrogen receptor (ER) and oxytocin receptor (OTR) in the luminal and superficial glandular epithelia to abrogate the production of luteolytic prostaglandin F(2alpha) (PGF(2alpha)) pulses. Subcutaneous (s.c.) injections of recombinant ovine (o) IFNtau appear to extend the interestrous interval by altering uterine PGF(2alpha) response to oxytocin. The present study tested the hypothesis that antiluteolytic effects of roIFNtau injected into the uterine lumen (paracrine) or s.c. (endocrine) are equivalent in suppressing expression of endometrial ER and OTR and inducing uterine expression of type I IFN-regulated Mx and ubiquitin cross-reactive proteins (UCRP). Sixteen cyclic ewes were fitted with uterine catheters on Day 5 (Day 0 = estrus), were assigned randomly to receive treatment with control proteins or roIFNtau (2 x 10(7) antiviral units/day) by either intrauterine or s.c. injections from Days 11 to 15, and were ovariohysterectomized on Day 16. Results indicated that expression of ER and OTR mRNAs in endometrial epithelium was suppressed by intrauterine but not by s.c. injections of roIFNtau. Intrauterine injections of roIFNtau increased expression of Mx and UCRP mRNA in the endometrium. Subcutaneous injections of roIFNtau increased endometrial Mx mRNA levels but not UCRP mRNA. Unexpectedly, intrauterine and s.c. injections of roIFNtau were equally effective in inducing expression of Mx and UCRP mRNA in the corpus luteum. Although s.c. injections of roIFNtau induced Mx mRNA in the endometrial epithelium, s.c. injections of roIFNtau did not abrogate activation of the uterine luteolytic mechanism by suppressing epithelial ER and OTR expression. Therefore, results of this study failed to support the assumption that endocrine roIFNtau mimics antiluteolytic effects of paracrine IFNtau to improve pregnancy rates in sheep.

Nematode burdens and cellular responses in the abomasal mucosa and blood of Florida Native, Rambouillet and crossbreed lambs

This experiment was carried out to compare the worm burden and cellular responses in the abomasal mucosa and blood of Florida Native and Rambouillet lambs and also in animals produced by crosses of these two breeds (generations F1 and F2). Animals were exposed to infection by gastrointestinal nematodes on three different occasions. The first infection was natural, occurring while they were suckling lambs. After weaning, they were kept indoors for 53 days and then were allowed to graze a contaminated pasture for 50 days for a second natural infection. The third infection was an artificial challenge with 6000 Haemonchus contortus infective larvae. The highest mean fecal egg counts (FEC) values were found in Rambouillet lambs followed in decreasing order by F1, F2 and Florida Native lambs. Throughout the trial, most of the high mean packed cell volumes and plasma protein levels were recorded in the F2 lambs; in contrast, most of the low values were found in the Rambouillet lambs. During the natural infection period, the highest percentages of larvae in the fecal cultures of the lambs were Haemonchus. However, high percentages of Trichostrongylus larvae were found particularly in Florida Native lambs. The mean number of blood eosinophils increased after the artificial challenge, reached a peak 21 days after infection and then declined. The highest and lowest blood eosinophil means were recorded in F2 and Florida Native lambs, respectively. The H. contortus burden was significantly higher in Rambouillet and in F1 lambs than in Florida Native and F2 lambs (p < 0.05), while no significant differences were recorded among eosinophil, mast cell and globule leucocyte counts in the abomasal mucosa (p > 0.05). The highest correlation coefficient recorded at the end of this study was between FEC and worm burden (r = 0.7). These two parameters showed a moderate negative correlation with PCV, plasma protein and mast cell counts in the abomasal mucosa. The results obtained in this study indicate that crossbreeding Florida Native and Rambouillet sheep can be a rapid way to combine and improve the characteristics of these two breeds. The parasitological results were promising, however, more studies will be necessary to verify the impact of crossbreeding in other traits.

Copper status of ewes fed increasing amounts of copper from copper sulfate or copper proteinate

The Cu status of mature, crossbred ewes fed two sources (CuSO4 vs. Cu proteinate) and three levels (10, 20, or 30 mg/kg) of dietary Cu was determined in a 73-d feeding trial. Ewes (n = 30) were fed a basal diet containing rice meal feed, cottonseed hulls, cottonseed meal, meat and bone meal, cracked corn, and vitamin-mineral supplements at 2.5% of BW to meet NRC requirements for protein, energy, macrominerals, and microminerals, excluding Cu. The basal diet contained 5 mg/kg Cu, 113 mg/kg Fe, .1 mg/kg Mo, and .17% S. Copper sulfate or Cu proteinate was added to the basal diet to supply 10, 20, or 30 mg/kg of dietary copper in a 2x3 factorial arrangement of treatments. Ewes were housed in 3.7- x 9.1-m pens in an open-sided barn. Blood samples were collected on d 28 and 73. Ewes were slaughtered on d 74, and liver and other tissues were collected to determine Cu concentrations. An interaction (P = .08) occurred between source and level for liver Cu. The interaction existed due to an increase in liver Cu concentrations when ewes were fed increasing dietary Cu from CuSO4 but not when fed Cu proteinate diets. There was no source x level interaction (P>.10) for the blood constituents measured. On d 73, plasma ceruloplasmin activity was greater (P<.05) in ewes fed Cu proteinate than in those fed CuSO4 (33.1 vs. 26.8 microM x min(-1) x L(-1)). Increasing the concentration of dietary Cu did not affect (P>.10) plasma ceruloplasmin. Packed cell volume (PCV), red blood cell count (RBC), white blood cell count, whole blood hemoglobin (wHb), plasma hemoglobin, and plasma Cu were similar between sources of Cu. Ewes fed 20 mg/kg Cu had lower (P<.05) PCV, RBC, and wHb than those fed 10 or 30 mg/kg Cu diets. Feeding up to 30 mg/kg Cu from these sources did not cause an observable Cu toxicity during the 73-d period.

Relationships among ewe milk production and ewe and lamb forage intake in Suffolk and Targhee ewes nursing single or twin lambs

Suffolk and Targhee ewes (30 each) with single or twin lambs were used in four periods beginning in late gestation and continuing through weaning to evaluate breed differences in milk production, lamb BW, and DMI by ewes and lambs. In Periods 1 (late gestation) and 2 (early lactation), ewes (Period 1) and ewes with lambs (Period 2) were individually penned, fed .45 kg of barley x ewe(-1) x d(-1) and allowed ad libitum access to chopped alfalfa. Ewes and lambs grazed native range in Periods 3 and 4. Grazed forage DMI was estimated using chromic oxide. Estimates of milk production were obtained by handmilking. Average lamb age was 4, 45, and 73 d at the beginning of Periods 2, 3, and 4, respectively. Milk production tended (P = .20) to be greater for Suffolk than for Targhee ewes. Targhee ewes produced 85% more (P = .001) wool than Suffolk ewes. From 33 d prepartum to 89 d postpartum, Suffolk ewes consistently weighed more (P = .001) than Targhee ewes. Suffolk ewe BW loss (-.15 kg/d) was greater (P = .01) than Targhee ewe BW loss (-.02 kg/d) from 33 d prepartum to 6 d postpartum. From 6 to 89 d postpartum BW gain did not differ (P = .69; .05 kg/d) between breeds. From birth to 89 d postpartum, Suffolk lambs consistently weighed more than Targhee lambs (P = .003). From birth to 89 d postpartum, ADG was greater for Suffolk than for Targhee lambs (P = .006). Targhee ewes consumed 25% more (P = .01) feed over the course of the study than did Suffolk ewes. Grazed forage DMI by Targhee lambs was 26% greater (P = .01) than DMI by Suffolk lambs. When meat production is the primary income from sheep, one potential advantage of Suffolks compared with Targhees is more rapid gain with less feed intake.

Relationships among ewe milk production and ewe and lamb forage intake in Targhee ewes nursing single or twin lambs

Targhee ewes with single or twin lambs were used in four trials during early lactation through weaning to evaluate ewe milk production (MP), kilograms of lamb weaned, and forage intake by ewes and lambs. During Trial 1, ewes with lambs were individually penned, fed .45 kg of barley-ewe-1.d-1 and allowed ad libitum access to chopped alfalfa hay. Trials 2, 3, and 4 were conducted on three different types of Western range environments. Forage intake of ewes in Trials 2, 3, and 4 and of lambs in Trials 3 and 4 was estimated using chromic oxide. Estimates of milk production were obtained by hand-milking. Average lamb age was 4, 50, 78, and 106 d at the beginning of Trials 1, 2, 3, and 4, respectively. Milk production was greater (P = .01) for ewes nursing twins than for those nursing singles at d 4 and 14 in Trial 1. In Trials 2, 3, and 4, all ewes had similar (P > .18) milk production. Ewe DMI during Trials 1 and 2 was greater (P < .05) for ewes nursing twin lambs than for those nursing singles. There was no difference (P > .88) in DMI between ewes with single and those with twin lambs in Trials 3 and 4. Forage DMI by twin lambs, expressed as either kilograms.ewe-1.day-1 or percentage of lamb BW, was higher (P = .01) than intake by single lambs in Trials 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of barley variety and restricted versus ad libitum intake on rate, site, and extent of digestion by wethers fed a high-energy diet

Twelve ruminally cannulated wethers (four with duodenal cannulas) were used in a replicated 4 x 4 Latin square to investigate effects of barley variety and restricted vs ad libitum intake on site, rate, and extent of digestion. Diets were based on Ottus (52.7% starch; O) or Steptoe (56.7% starch; S) barley fed at either 90% of prestudy ad libitum feed intake (R) or ad libitum consumption (A). Diets were formulated to be equal in starch content (38%). Periods consisted of 10 d for adaptation followed by 10 d in which fecal, duodenal, ruminal, and in situ collections were made. With the exception of ruminal starch digestion, barley variety did not interact with level of feed intake (P > .26). Intake of OM was 1,009, 996, 1,124, and 881 g.wether-1.d-1 for O, S, A, and R, respectively. Intake by R wethers of OM and starch was 78% (P < .01) of intake by A wethers. Duodenal flow of OM and ruminal pH were not affected (P > .28) by either intake restriction or barley variety. Although restricted intake did not affect ruminal (P = .84) and duodenal (P = .39) ammonia nitrogen, the O barley had higher (P = .01) ruminal and duodenal ammonia nitrogen than did S barley. Restricted intake had no effect (P > .30) on rate of ruminal barley digestion, ruminal and total tract starch digestion, or total tract OM digestion. This may be due to the rapid digestion rate of barley.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of cell-substrate adhesion by a centrifugal method

A centrifugal method has been evaluated for measuring the strength of Vero Green Monkey kidney cell adhesion to growth surfaces. The centrifugal force necessary to remove cells gave a quantitative measure of cell adhesion and hence the quality of the growth surface. After being subjected to high gravity forces, both the remaining attached cells and the detached cells were viable, indicating the detachment process did not simply rupture the cell. Electron microscope examination of growth surfaces after cell detachment suggested that remnants related to filopodia remained.

Surface treatments and cell attachment

Photoelectron spectroscopic examination of treated plastic surfaces showed that surface oxidation, primarily as carboxyl groups, was responsible for formation of good growth surfaces. Gas-plasma studies indicated that only very short exposures were required and that the effect was confined to a thin surface layer that produced adhesive surfaces. Highly adhesive surfaces were produced using oxidizing chemicals. Studies with a polymeric ester demonstrated the importance of unesterified carboxyl groups for high adhesiveness.

Applications of fluorophore-containing microbial growth media

Media containing the fluorogenic compound 8-anilino-1-naphthalene sulfonic acid may be used to discriminate between gram-positive and gram-negative bacteria and to differentiate between various species of bacteria. Fluorescent light emitted from colonies of gram-negative bacteria on 8-anilino-1-naphthalene sulfonic acid-containing agar was visually more intense than that on gram-positive bacteria. The emitted light from the gram-negative bacteria differed in wave-lengths from that of light emitted by colonies of gram-positive bacteria. The fluorescent intensity of colonies on complete 8-anilino-1-napthalene sulfonic acid agar supplemented with 1% of single substrates varied depending on the bacterial species, thus allowing the development of profiles used to identify 12 different species.

Fluorophores as visualization aides in agar growth media

A survey of 26 fluorophores revealed 5 which were non-inhibitory to Staphylococcus aureus and Escherichia coli and produced low background and high colony fluorescence.

Stable messenger ribonucleic acid and germination of Myxococcus xanthus microcysts

We have examined germination, protein synthesis and ribonucleic acid (RNA) synthesis by microcysts of the fruiting myxobacterium Myxococcus xanthus. The morphological aspects of microcyst formation were completed at about 2 hr after induction had begun. In such microcysts, germination, RNA synthesis, and protein synthesis were inhibited by actinomycin D (Act D). At 6 hr after induction, germination and protein synthesis had become relatively resistant to Act D, whereas RNA synthesis was inhibited by about 95%. Experiments with (3)H-Act D indicated that the deoxyribonucleic acids of both young and old microcysts bind Act D equally. Resistance of germination to Act D was acquired 4 to 5 hr after induction of microcyst formation, and was due to an Act D-sensitive synthesis at that time. Vegetative cells and microcysts were pulsed with uridine-5-(3)H and chased for 60 min; the RNA was extracted and analyzed by means of sucrose density gradient centrifugation and gel electrophoresis. Both microcysts and vegetative cells were found to contain grossly the same types of RNA in the same proportions. RNA pulse-labeled in microcysts was more stable than that in vegetative cells. No particular portions of the microcyst pulse-labeled RNA were selectively stabilized. These data indicate that a stable messenger RNA required for synthesis of germination proteins was synthesized during microcyst formation. This may be the same as the RNA synthesized 4 to 5 hr after initiation of microcyst formation. We suggest that the existence of such stable messenger RNA in microcysts is consistent with the limited biosynthetic activities of such cells.

Microcyst germination in Myxococcus xanthus

Germination of glycerol-prepared microcysts of Myxococcus xanthus was studied. The sequence of morphological events during germination resembled that of germinating fruiting body-microcysts. The turbidity drop of a culture of germinating microcysts could be described by McCormick's formula derived for germinating Bacillus spores. The rate of uptake of labeled glycine and acetate did not change during germination. Temperature, aeration, and pH optima for germination were the same as for vegetative cell growth. Germination was induced by protein hydrolysates and the individual amino acids glycine, alanine, valine, aspartic acid, and glutamic acid. A number of organic compounds, including sugars, alcohols, aldehydes, ketones, organic acids, and chelating agents, did not induce germination. The inorganic ions HPO(4) (2-), Mg(++), Ca(++), and NH(4) (+) induced germination, although ionic strength was not a factor. Microcysts incubated in distilled water at concentrations greater than about 10(9) cells/ml germinated; supernatant fluid from such suspensions (germination factor) induced germination of less concentrated suspensions. The activity of germination factor was resistant to boiling, but was lost on charring and dialysis. Germination of microcysts and growth of vegetative cells was equally sensitive to a variety of metabolic inhibitors, including penicillin and chloramphenicol. Germination was more resistant than vegetative growth to inhibition by antibiotics of the streptomycin family and by actinomycin D.