Effects of exogenous progesterone and cloprostenol on ovarian follicular development and first ovulation in prepubertal heifers

The objective of this study was to determine the effects of progesterone and cloprostenol (a PGF_2α analogue) on ovarian follicular development and ovulation in prepubertal heifers. In Experiment 1, crossbred Hereford heifers (Bos taurus; 10 to 12 mo old, 255 to 320 kg) were assigned randomly to three groups and given (1) an intravaginal progesterone-releasing insert (CIDR; P group, n = 13); (2) a CIDR plus 500 μg cloprostenol im (PGF_2α analogue) at CIDR removal (PPG group, n = 11); or (3) no treatment (control group, n = 14). The CIDR inserts were removed 5 d after follicular wave emergence. Progesterone-treated heifers (P and PPG groups) had a larger dominant follicle than that of the control group (P = 0.01). The percentage ovulating was highest in the PPG group (8 of 11, 73%), intermediate in the P group (4 of 13, 31%), and lowest in the control group (1 of 14, 7%; P < 0.02). In Experiment 2, 16 heifers (14 to 16 mo old, 300 to 330 kg) were designated to have follicular wave emergence synchronized with either a CIDR and 1 mg estradiol benzoate im (EP group, n = 8) on Day 0 (beginning of experiment) or by transvaginal ultrasound-guided ablation of all follicles ≥5 mm on Day 3 (FA group, n = 8). On Day 7, CIDRs were removed in the EP group, and all heifers received 500 μg cloprostenol im. Ovulation was detected in 6 of 8 heifers (75%) in both groups. In summary, the use of PGF_2α with or without exogenous progesterone treatment increased the percentage ovulating in heifers close to spontaneous puberty.     

Inhibition of prostaglandin biosynthesis during postluteolysis and effects on CL regression, prolactin, and ovulation in heifers

The beginning of postluteolysis (progesterone, <1 ng mL⁻¹) in heifers was targeted by using 8 h after ultrasonic detection of a 25% decrease in CL area (cm²) and was designated Hour 0. Flunixin meglumine (FM; n = 10) to inhibit PGF_2α secretion or vehicle (n = 9) were given intramuscularly at Hours 0, 4, 8, 16, 24, 32, and 40. The dose of FM was 2.5 mg/kg at each treatment. Blood sampling and measurement of the CL and dominant follicle were done every 8 h beginning 14 days postovulation in each group. Blood samples for detection of pulses of PRL and pulses of a metabolite of PGF_2α (PGFM) were obtained every hour for 24 h beginning at Hour 0. Pulse concentrations of both PGFM and PRL were lower in the FM group than in the vehicle group. Concentration of PRL was greatest at the peak of a PGFM pulse. Neither CL area (cm²) nor progesterone concentration differed between groups during Hours 0 to 48 (postluteolysis). Ovulation occurred in nine of nine heifers in the vehicle group and in three of 10 heifers in the FM group. The anovulatory follicles in the FM group grew to 36.2 ± 2.9 mm, and the wall became thickened from apparent luteinization. The hypothesis that PGF_2α was involved in the continued P4 decrease and structural CL regression during postluteolysis was not supported. However, the hypotheses that pulses of PGFM and PRL were temporally related and that systemic FM treatment induced an anovulatory follicle were supported.     

Neither duration of progesterone insert nor initial GnRH treatment affected pregnancy per timed-insemination in dairy heifers subjected to a Co-synch protocol

Our objectives were to: 1) compare response to cloprostenol, synchrony of ovulation, and pregnancy per timed-AI (P/TAI) in a 5 d versus a 7 d Co-synch + PRID protocol (Experiment 1); and 2) investigate whether the initial GnRH is necessary to achieve acceptable P/TAI in a 5 d Co-synch + PRID protocol (Experiment 2) in dairy heifers. In Experiment 1, 64 Holstein heifers, 15 to 17 mo, were assigned by age to receive 100 μg of GnRH and a PRID for 5 or 7 d (PRID5 and PRID7, respectively). At PRID removal 500 μg of cloprostenol (PGF) was given i.m. Heifers received the second GnRH treatment concurrently with TAI at 72 (PRID5) or 56 (PRID7) h after PRID removal. Transrectal ultrasonography monitored ovarian dynamics, ovulation synchrony, and pregnancy status (28 and 45 d after TAI). Plasma progesterone concentrations were determined at PRID removal and TAI. Five of seven heifers that ovulated before TAI became pregnant, and only two heifers did not respond to PGF treatment in the PRID5 group. Five PRID5 and 2 PRID7 heifers failed to ovulate after the second GnRH. However, P/TAI did not differ between PRID5 (59.4%) and PRID7 (58.1%). Overall ovulation response to first GnRH treatment was only 31.7%, and a larger proportion of heifers that did not ovulate became pregnant (65.1 versus 45.0%). In Experiment 2, 56 Holstein heifers, assigned as in Experiment 1, were subjected to a PRID5 protocol with (PRID5G) or without (PRID5NoG) GnRH at PRID insertion; all heifers were TAI 72 h after PRID removal. Transrectal ultrasonography and progesterone determinations were performed as in Experiment 1. Pregnancy per TAI did not differ whether or not heifers received GnRH at PRID insertion (67.9 versus 71.4%). Consistent with our previous findings, seven of nine heifers that ovulated before TAI became pregnant, and only two heifers did not respond to PGF treatment. Combining both experiments, length of proestrus but not ovulatory follicle diameter was identified as a significant predictor of probability of pregnancy 28 d after TAI, with a maximum predicted probability of 80.1% when the length of proestrus was 3 d. In summary, a PRID5 protocol resulted in comparable P/TAI to a PRID7 protocol. Most of the heifers that ovulated before TAI in the PRID5, PRID5G, and PRID5NoG protocols became pregnant. More than one PGF or a GnRH treatment at PRID insertion in a 5 d Co-synch + PRID protocol was not required to achieve acceptable P/TAI in dairy heifers.     

Influence of low plasma progesterone concentrations on the release of prostaglandin F2α during luteolysis and oestrus in heifers

A study was conducted to determine the effect of suprabasal plasma concentrations of progesterone on the release of prostaglandin F_2α (PGF_2α) at luteolysis and oestrus. Heifers received silicone implants containing 2.5 (n = 4), 5 (n = 4), 6 (n = 3), 7.5 (n = 3), 10 (n = 4), or 15 (n = 3) g of progesterone, or an empty implant (controls, n = 4) between Days 8 and 25 post ovulation. Blood was collected frequently between Days 14 and 28 and assayed for progesterone and 15-ketodihydroprostaglandin F_2α. Basal progesterone concentrations in control heifers did not differ from those in heifers with 2.5- or 5-g implants and remained around 0.4−0.5 nmol l⁻¹ until ovulation in all three groups. In the heifers treated with 6–15 g of progesterone, basal concentrations were maintained at higher (P < 0.05) levels compared with those in the controls, ranging from 0.8 to 1.6 nmol 1⁻¹. The effect of these elevated progesterone levels was to delay ovulation by prolonging the growth of the ovulatory follicle, which continued growing until the implant was removed. In all experimental groups, the first significant increase of the PGF_2α metabolite occurred between Days 15.3 and 16.3 (P > 0.05) and was associated with the onset of a decrease in progesterone concentrations, which had reached levels below 3 nmol 1⁻¹ by Days 17.4−19.1. PGF_2α metabolite peaks associated with luteolysis were frequent until Day 20. In the period from Day 20 until implant removal, sporadic peaks were observed, ranging in number from 1.0 ± 1.2 (mean ± SEM) in the control group to 3.0 ± 1.4 peaks in the heifers treated with 7.5 g of progesterone (P > 0.05). The number of PGF_2α metabolite peaks during that period was higher (P < 0.05) in heifers treated with 10 and 15 g than in controls. A positive correlation was found between the basal concentration of progesterone and the number of PGF_2α peaks after luteolysis (r = 0.54; P < 0.01). Plasma progesterone concentrations above approximately 1.4 nmol l⁻¹ were able to maintain the release of PGF_2α until the progesterone implants were removed and plasma levels decreased to basal values. These heifers had a preovulatory PGF_2α release pattern resembling that found in repeat breeder heifers.     

Differences between single and paired heifers in residency in functional areas, length of travel path, and area used throughout days 1–6 after integration into a free stall dairy herd

The integration of heifers into free stall dairy herds is a frequent management procedure, but little systematic research has been conducted on its effect on cow behavior. Previous studies mainly focused on aggressive interactions, but it is also of interest how integration affects the spatial distribution of both the cows in the herd and the integrated heifers. In the present study we integrated a single and a pair of heifers on each of six Swiss working farms in a balanced order. Using an automatic tracking system, we recorded the positions of all the cows and of the integrated heifers at 1 min intervals for six continuous 24 h periods. From these data we calculated the proportion of time the animals spent in the activity area, at the feed rack and in the lying cubicles, their average path length and the area of the barn that they used. We then compared the behavior of the integrated heifers with that of the cows in the introductory weeks. We also compared the behavior of the cows recorded in the control weeks directly preceding the integration and in the introductory weeks. For evaluation we used linear mixed-effects models. Singly integrated heifers spent a higher proportion of time in the activity area (0.29 vs. 0.14; P < 0.001) and a lower proportion of time in the lying area (0.40 vs. 0.53; interaction with day, P = 0.011) than the cows, whereas the heifers of the pairs mainly spent a lower proportion of time in the feeding area than the cows (0.23 vs. 0.32; interaction with day, P = 0.044). Average path length was longer for the integrated heifers soon after introduction but approached the values of the cows later on (interaction with day, P = 0.012). The total barn area used by a given animal was largest in the cows and was reduced in heifers integrated singly or in pairs (cows: 341/373 m², pairs: 306 m², single heifer: 333 m²; P = 0.055). Cows were little influenced in their space use by the integration of a single or pair of heifers. In summary, the behavior of the singly integrated heifers differed more markedly from that of the cows than the behavior of the heifers introduced in pairs during the introductory week. We would therefore recommend integrating pairs rather than single heifers into herds of dehorned dairy cows to ease their integration.     

Effect of GnRH administration, combined with the ram effect, on the occurrence of ovulation and pregnancy during the transition period from anoestrus in crossbred ewes

The effect of a GnRH analogue (buserelin) combined with the ram effect on the reproductive efficiency of ewes was investigated in 105 cross-bred fat tailed ewes, during the transition period from anoestrus to the natural breeding season. Plasma progesterone concentration was used in the assessment with regard to ovulation and pregnancy. Ewes were maintained on natural pastures composed of medium to low quality forages, and received supplementation (40% alfalfa hay: 60% wheat straw) ad libitum, plus 100–300 g barley grain per head per day. Ewes were isolated from the rams for at least two months and then kept in close proximity of the rams for one week, before the introduction of the rams. The ewes were randomly divided into three equal groups (n = 35 per group). With the introduction of the rams into the flock (day 1) one group was considered as the control and the other two groups were treated with 4.2 μg (low dose) and 8.4 μg (high dose) buserelin on days 5 and 19, respectively. Blood samples were collected on days 5, 12, 26 and 120 after ram introduction for determining the plasma progesterone levels. On day 12 (one week after treatment) the high dose GnRH group recorded significantly lower plasma P4 concentrations (P < 0.05), compared with the control group (1.0 ± 0.1 ng/ml versus 2.4 ± 0.4 ng/ml). On the same day the low GnRH dose group recorded intermediate P4 concentrations, recording no significant differences with the other two groups. The high dose group recorded a significantly (P < 0.05) higher proportion of non-ovulated ewes (61.8%), compared to the control (32.3%) and low dose (31.4%) groups on day 12 of the study. At days 5 and 26 these differences were not significant, but the proportion of non-ovulated ewes was higher in the high dose buserelin treatment group. The percentage of pregnant (plasma P4 > 2.5 ng/ml) and non-pregnant (plasma P4 ≤ 2.5 ng/ml) ewes at day 120 of the study was not statistically different between the treatment groups. The pregnancy rate was highest in the control group (97.1%), when compared to the treated ewes (94.3% and 88.6% in low dose and high dose treatment groups, respectively). Treatment with buserelin combined with the male effect during the breeding season negatively affected the plasma P₄ concentration, reducing the reproductive performance of the ewe treatment groups.     

Effects of one versus two doses of prostaglandin F2alpha on AI pregnancy rates in a 5-day, progesterone-based, CO-Synch protocol in crossbred beef heifers

The present study determined whether a 5-d progesterone-based CO-Synch protocol with a single dose of prostaglandin F_2α (PGF) at progesterone withdrawal on Day 5, would yield a timed AI pregnancy rate similar to two doses of PGF given 6 h apart on Day 5. Angus cross beef heifers (N = 562) at six locations were used. All heifers received 100 µg of gonadorelin hydrochloride (GnRH) and a controlled internal drug release (CIDR) insert on Day 0. Within farm, heifers were randomly allocated to receive one dose of 25 mg dinoprost (PGF) at CIDR removal on Day 5 (1 PGF; N = 264), or two doses of 25 mg PGF, with the first dose given on Day 5 at CIDR removal, and the second dose 6 h later (2 PGF; N = 298). Most heifers (N = 415) received a heat detector patch at CIDR removal. After CIDR removal, heifers were observed twice daily through Day 7 for estrus and heat detector aid status was recorded. On Day 8, heifers were given 100 µg of GnRH, heat detector aid status was recorded, and heifers were inseminated approximately 72 h after CIDR removal. Accounting for significant variables such as location (P < 0.01), heifers in estrus at or prior to AI (P < 0.001), and a treatment by location interaction (P < 0.01), two doses of PGF on Day 5 tended to have higher pregnancy rates to timed AI compared to those that received one dose of PGF (P = 0.06). In conclusion, heifers given two doses of PGF at CIDR removal on Day 5, in a 5-d CIDR-CO-Synch protocol, tended to have a higher pregnancy rate than those that received only one dose of PGF.     

The effect of a progesterone (P4) intravaginal device (CIDR) on resynchronisation of oestrus and embryonic loss in previously timed inseminated dairy heifers

A study was done to evaluate the effect of using progesterone (P4) intravaginal device (CIDR: controlled internal drug-releasing dispenser) to synchronise the return to oestrus of previously timed inseminated (TAI) dairy heifers, and to evaluate embryo survival and pregnancy rate (PR) in the return to oestrus heifers. At the onset of the artificial insemination (AI) breeding period (day -9), heifers were randomly assigned into two groups (treated group CGPG, n = 79) and (control group GPG, n = 83). Every heifer in both groups was injected with gonadotropin-releasing hormone (GnRH) agonist and prostaglandin F2-alpha (PGF2α) as follows: GnRH on day -9; PGF2α on day -2; GnRH and TAI on day 0. Heifers in both groups received TAI within 30 min after the second GnRH injection. Artificial insemination at first breeding was conducted for all heifers during 55 days from day 0. On day 14 after timed insemination, every heifer in the CGPG group received CIDR device for 6 days. Within 3 days after CIDR removal, more heifers in CGPG group showed oestrus within 1.9 days compared to heifers that showed oestrus within 2.9 days in the control. Within 10 days after CIDR removal, more heifers in the CGPG group showed oestrus within 2.4 days compared to heifers that showed oestrus within 6.7 days in the control. PRs on days 30 and 55 were not different between both groups, while PR on day 55 during September were higher (P = 0.032) in CGPG group (58.0%) than GPG group (37.0%). In addition, PR from first to second AI was higher (P = 0.037) for CGPG group (79.8%) than for GPG group (65.1%) but it was similar after that. Pregnancy losses between days 30 and 55 tended to be lower (P = 0.089) for the CGPG group (12.7%) compared to 25.1% for the GPG group. Interval between first and second AI was lower (P = 0.052) for the CGPG group (27.5 ± 1.6 days) compared to 31.6 ± 1.3 days for heifers in the GPG group but no differences were detected for intervals from second to third AI and from third to fourth AI between the two groups. Number of services per pregnancy was not different between CGPG and GPG groups. Results indicate that the CIDR device improved synchronisation to return to oestrus and increased PR to first AI during high temperature months by reducing embryonic losses.     

The effects of GnRH analogue (buserelin) or hCG (Chorulon) on Day 12 of pregnancy on ovarian function, plasma hormone concentrations, conceptus growth and placentation in ewes and ewe lambs

The objectives of this study were to determine the effect of GnRH analogue (buserelin) or human chorionic gonadotrophin (hCG, Chorulon) treatment on Day 12 of pregnancy on ovarian function, plasma hormone concentrations, conceptus growth and placentation in ewes and ewe lambs. After oestrus synchronization with progestagen sponges and eCG, all the animals were mated with fertile rams. Both ewes and ewe lambs (20 per treatment group) were given either normal saline or 4 microg GnRH or 200 IU hCG on Day 12 post-mating. Pre- and post-treatment plasma hormone concentrations were determined in seven pregnant animals per treatment group in samples collected 1h before and 0, 2, 4, 6, 8, 24, 48 and 72 h after treatment. Overall mean progesterone concentrations were higher (P<0.001) in ewes as compared with ewe lambs in saline-treated controls. GnRH or hCG treatment increased (P<0.001) mean plasma progesterone concentrations in both age groups, however, post-treatment concentrations were significantly (P<0.05) higher in ewes than in ewe lambs. Oestradiol concentrations were similar in the two control groups. In ewes, but not in ewe lambs, both GnRH and hCG treatments significantly (P<0.05) increased the mean oestradiol concentrations above pre-treatment levels. Moreover, post-treatment oestradiol concentrations in GnRH- and hCG-treated animals were significantly (P<0.05) higher than those in the saline-treated controls. LH release in response to GnRH treatment was greater (P<0.05) in ewes than in ewe lambs, whereas FSH release in ewes was less (P<0.05) than that of ewe lambs. The effects of GnRH or hCG on conceptus growth and placentation was determined at slaughter on Day 25. In ewes, GnRH treatment increased (P<0.05) luteal weight, amniotic sac width and length, and crown-rump length compared with controls, but had no effect on these parameters in ewe lambs. In ewes, hCG treatment also enhanced (P<0.05) luteal weight, amniotic sac width and length, crown-rump length, embryo weight and number of placentomes as compared with controls. In ewe lambs, there was no difference (P<0.05) between hCG and control groups in luteal weight, embryo weight and amniotic sac width but crown-rump length, amniotic sac length and the number of placentomes forming the placenta were greater (P<0.05). In conclusion, GnRH or hCG treatment on Day 12 of pregnancy can increase ovarian function, conceptus growth and placental attachment in ewes. However, these treatments were less effective in ewe lambs.     

Syntheses, crystal structures and magnetic properties of trinuclear and [3 × 1 + 1 × 2] pentanuclear complexes derived from a compartmental ligand: Role of solvent on nuclearity and number of components

Reaction of [Cu^IIL⊂(H₂O)] (H₂L = N,N′-ethylenebis(3-ethoxysalicylaldimine)) with nickel(II) perchlorate in 1:1 ratio in acetone produces the trinuclear compound [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂ (1). On the other hand, on changing the solvent from acetone to methanol, reaction of the same reactants in same ratio produces the pentametallic compound [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂·2[Cu^IIL⊂(H₂O)]·2MeOH (2A), which loses solvated methanol molecules immediately after its isolation to form [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂·2[Cu^IIL⊂(H₂O)] (2B). Clearly, formation of 1 versus 2A and 2B is solvent dependent. Crystal structures of 1 and 2A have been determined. Interestingly, compound 2A is a [3 × 1 + 1 × 2] cocrystal. The cryomagnetic profiles of 1 and 2B indicate that the two pairs of copper(II)···nickel(II) ions in the trinuclear cores in both the complexes are coupled by almost identical moderate antiferromagnetic interaction (J = −22.8 cm⁻¹ for 1 and −26.0 cm⁻¹ for 2B).     

The orphan nuclear receptor SF-1 is involved in the effect of PCBs,DDT, and DDE on the secretion of steroid hormones and oxytocin from bovine luteal cells during the estrous cycle in vitro

The orphan receptor steroidogenic factor-1 (SF-1) is involved in the regulation of ovarian steroidogenesis in cows. It is hypothesized that estrogen-like chlorinated compounds might affect SF-1, and thus impair the function of the ovary. Bovine luteal cells from the estrous cycle (Days: 1–5, 6–10, 11–15, and 16–19) were treated for 50 hours with DDT, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene, 3,3′4,4′-tetrachlorobiphenyl or 2′2′4,4′,5,5′-hexachlorobiphenyl (each at a dose of 10 ng/mL). Luteal cells were also treated with 4-(heptyloxy)phenol (1 × 10⁻⁷ M), an SF-1 agonist, and F0160 (1 × 10⁻⁶ M), an SF-1 blocker, jointly or separately. The secretion of progesterone and oxytocin and the expression of oxytocin precursor (NP-I/OT) messenger RNA were increased (P < 0.05) by all studied xenobiotics and 4-(heptyloxy)phenol, although they were inhibited (P < 0.05) by F0160. However, the xenobiotics did not affect (P > 0.05) SF-1 messenger RNA expression. In summary, SF-1 is involved in the adverse effect of chlorinated xenobiotics on the regulation of the bovine CL.     

The partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows

The objectives of the study were to determine the effect of the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea on the performance, metabolism and whole-tract digestibility in mid-lactation dairy cows. Forty-two Holstein–Friesian dairy cows were allocated to one of three dietary treatments in each of three periods of 5 weeks duration in a Latin square design. Control (C) cows were offered a total mixed ration based on grass and maize silages and straight feeds that included 93 g/kg dry matter (DM) soyabean meal and 61 g/kg DM rapeseed meal. Cows that received either of the other two treatments were offered the same basal ration with the replacement of 28 g/kg DM soyabean and 19 g/kg DM rapeseed meal with either 5 g/kg DM feed grade urea (U) or 5.5 g/kg DM of the slow-release urea (S; Optigen^R; Alltech Inc., Kentucky, USA), with the content of maize silage increasing. There was no effect (P > 0.05) of dietary treatment on DM intake, which averaged 22.5 kg/day. Similarly, there was no effect (P > 0.05) of treatment on daily milk or milk fat yield but there was a trend (P = 0.09) for cows offered either of the diets containing urea to have a higher milk fat content (average of 40.1 g/kg for U and S v. 38.9 g/kg for C). Milk true protein concentration and yield were not affected by treatment (P > 0.05). Milk yield from forage and N efficiency (g milk N output/g N intake) were highest (P < 0.01) in cows when offered S and lowest in C, with cows receiving U having intermediate values. Cows offered S also tended to have the highest live weight gain (0.38 kg/day) followed by U (0.23 kg/day) and C (0.01 kg/day; P = 0.07). Plasma urea concentrations were higher (P < 0.05) at 2 and 4 h post feeding in cows when offered U and lowest in C, with animals receiving S having intermediate values. There was no effect (P > 0.05) of treatment on whole-tract digestibility. In conclusion, the partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea can be achieved without affecting milk performance or diet digestibility, with the efficiency of conversion of dietary N into milk being improved when the slow-release urea was fed.     

The effects of starvation and repeated disturbance on mass loss,pit construction,and spatial pattern in a trap‐building predator

1. Starvation tolerance is an important trait for animals, as most will encounter starvation within their lifetime. Sit‐and‐wait predators are better adapted to starvation owing to their naturally low encounter rate with prey. 2. Starvation tolerance was studied under three levels of disturbance of wormlion larvae, a strict sit‐and‐wait predator that constructs pits. 3. Frequently disturbed wormlions constructed pits less often, and larger individuals continued to construct pits more frequently than smaller ones. It was expected that a high disturbance level would lead to a high rate of mass loss, however, surprisingly, the rate of mass loss was not higher for the frequently disturbed group. This suggests that the energetic cost of pit construction and maintenance is not as high as previously suggested for other pit‐building predators. 4. Larger individuals tolerated starvation better, in losing a lower proportion of their initial body mass and having higher chances of survival throughout the experiment. 5. The effect of starvation on the distance to neighbours was also investigated, and starved individuals were expected to maximise this distance in order to avoid interference competition. However, wormlions were usually clumped, and starvation or feeding had no effect on the pits' spatial pattern, suggesting that interference competition plays a minor role in this species. 6. Generally, wormlion larvae demonstrated a high starvation tolerance and low mortality rates even after 9 weeks of starvation.     

The effects of oligomycin on content of adenylates in mesophyll protoplasts,chloroplasts and mitochondria from Pb<Superscript>2+</Superscript> treated pea and barley leaves

The effects of oligomycin on photosynthesis and respiration in relation to ATP production in chloroplasts and mitochondria were investigated in protoplasts isolated from the detached pea (Pisum sativum L cv. Iłowiecki.) and barley (Hordeum vulgare L. cv. Gunilla) leaves treated 5 mM Pb(NO₃)₂. The oligomycin (OM), an inhibitor of oxidative phosphorylation at 0.1 μM concentration caused the inhibition of photosynthesis rate in the protoplasts from both the control and the Pb-treated pea leaves. The respiration rate and ATP/ADP ratio in the protoplasts and the activity of ATPase in mitochondria, were also diminished in the control protoplasts. These effects were not observed in the protoplasts and mitochondria isolated from the Pb-treated leaves. Oligomycin, an inhibitor of photophosphorylation at 10 μM concentration decreased ATPase activity in chloroplasts from both the control and the Pb- treated leaves. Using the method of rapid fractionation of barley protoplasts it was shown that the ATP/ADP ratio in the mitochondria from Pb-treated leaves was largely suppressed (from 1.8 to 0.4) by OM under nonphotorespiratory conditions (high CO₂), whereas under photorespiratory conditions (low CO₂) this ratio was high (5.3) and under OM decreased less (to 3.1). Our results indicate that oligomycin, in organelle isolated from Pb-treated leaves, had no inhibitory effect on the mitochondrial ATPase, whereas it inhibited chloroplasts ATPase. We suggest that Pb ions affected the catalytic cycle and/or conformational changes of ATPase in pea chloroplasts differently than in mitochondria. The differences in Pb responses may reflect fine mechanisms for the regulation of ATP production in the plant cells under stress conditions.     

The effects of organic solvents on the efficiency and regioselectivity of N‐acetyl‐lactosamine synthesis,using the β‐galactosidase from Bacillus circulans in hydro‐organic media

The enzymatic synthesis of N‐acetyl‐lactosamine (LacNAc) by the transgalactosylation of N‐acetyl‐D ‐glucosamine (GlcNAc), catalyzed by the β‐galactosidase from Bacillus circulans (BcβGal), was studied in hydro‐organic media, starting from o‐nitrophenyl‐β‐D ‐galactopyranoside (oNPG) as a galactosyl donor. Thermal stability and synthesis activity of BcβGal were shown to depend on the organic solvent polarity, characterized by its Log P value. BcβGal was thus most stable in 10% (v/v) t‐BuOH, an organic solvent found to have a stabilizing and/or weakly denaturing property, which was confirmed for high t‐BuOH concentrations. In the same manner, the optimal synthesis yield increased as the Log P value of the organic solvent increased. The best results were obtained for reactions carried out in 10% (v/v) pyridine or 2‐methyl‐2‐butanol, which gave 47% GlcNAc transgalactosylation yield based on starting oNPG, of which 23% (11 mM; 4.3 g/L) consisted in LacNAc synthesis. Furthermore, it was also established that both the GlcNAc transgalactosylation yield and the enzyme regioselectivity depended on the percentage of organic solvent used, the optimal percentage varying from 10 to 40% (v/v), depending on the solvent. This phenomenon was found to correlate mainly with the thermodynamic activity of water (a_w) in the aqueous organic solvent mixture, which was found to be optimal when close to 0.96, whatever the organic solvent used. Finally, this study highlighted the fact that the regioselectivity of BcβGal for 1‐4 linkage formation could be advantageously managed by controlling the a_w parameter. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Changes in tree community composition and structure of Atlantic rain forest on a slope of the Serra do Mar range,southeastern Brazil,from near sea level to 1000 m of altitude

Variations of tree species composition and community structure and their relationship with environmental variables are described for five sites of the Atlantic rain forest in Picinguaba, southeastern Brazil, distributed along an elevation gradient sampled by plots located at the altitudes of 2, 100, 300, 600 and 1000 m a.s.l. Sampled trees with DBH ≥ 5 cm were identified to species level and their diameter and height were measured. Environmental variables obtained for each plot included 11 topsoil variables and altitude. The residuals of all linear models were tested for spatial structure and multivariate analyses were performed to seek for relationships between the overall species’ abundances and selected environmental variables. Although both forest physiognomy and species’ abundances did change with altitude, this was clearly sharp only from the coastal plain (2 m) to 100 m, and from 600 m to the summit (1000 m). The three mid-slope sites (100, 300 and 600 m) were rather undifferentiated, though they were richer in species and had taller canopy trees. The altitude and the edaphic variables silt, clay, pH and total exchangeable bases (TEB) presented significant correlations with the variations in species’ abundances, while only pH and TEB were significantly correlated with species richness. The present study demonstrates for the first time that the composition and structure of Atlantic Forest can change accompanying the soil and altitude variations over short distances.     

The effects of condensed tannins derived from senescing <Emphasis Type="Italic">Rhizophora mangle</Emphasis> leaves on carbon,nitrogen and phosphorus mineralization in a <Emphasis Type="Italic">Distichlis spicata</Emphasis> salt marsh soil

Background and aims

Low nitrogen negatively affects soil fertility and plant productivity. Glucose-6-phosphate dehydrogenase (G6PDH) and Epichloë gansuensis endophytes are two factors that are associated with tolerance of Achnatherum inebrians to abiotic stress. However, the possibility that E. gansuensis interacts with G6PDH in enhancing low nitrogen tolerance of host grasses has not been examined.

Methods

A. inebrians plants with (E+) and without E. gansuensis (E?) were subjected to different nitrogen concentration treatments (0.1, 1, and 7.5 mM). After 90 days, physiological studies were carried out to investigate the participation of G6PDH in the adaption of host plants to low nitrogen availability.

Results

Low nitrogen retarded the growth of A. inebrians. E+ plants had higher total dry weight, chlorophyll a and b contents, net photosynthesis rate, G6PDH activity, and GSH content, while having lower plasma membrane (PM) NADPH oxidase activity, NADPH/NADP⁺ ratios, and MDA and H₂O₂ than in E? A. inebrians plants under low nitrogen concentration.

Conclusions

The presence of E. gansuensis played a key role in maintaining the growth of the A. inebrians plants under low nitrogen concentration by regulating G6PDH activity and the NADPH/NADP⁺ ratio and improving net photosynthesis rate.

     

The independent effects of heat,smoke and ash on emergence of seedlings from the soil seed bank of a heathy Eucalyptus woodland in Grampians (Gariwerd) National Park,western Victoria

Abstract The independent effects of smoke, ash, and wet and dry heat treatments on seedling emergence from the soil seed bank were tested for soils from fire-prone heathy woodlands in western Victoria. A total of 763 individuals from 56 species were recorded from the surface soil samples (which covered a total area of 1 m²). Both species richness and density of seedlings was greater for smoke- and heat-treated samples than for controls and ash-treated samples. However, only the density differences were significant. Mean seed bank densities for the smoke and heat treatments ranged from 855 ± 70m^?2 to 1080 ± 58 m^?2 and are similar to estimates obtained elsewhere in Australia for heat-treated soils from dry sclerophyll communities. Of the 56 species recorded, 46 occurred in the smoke and heat treatments but only 33 in the control and ash treatments. The sudden increase in surface soil pH, exchangeable cations and extractable phosphorus which was associated with the ash treatment did not act as a trigger for germination in any of the species recorded here. Chemical constituents from smoke do appear to provide a stimulus separate from the effects of heat, but were not identified with any particular taxa.     

The effects of Paraloid B‐72 and Butvar B‐98 treatment and organic solvent removal on δ13C, δ15N,and δ18O values of collagen and hydroxyapatite in a modern bone

Stable isotopes in bones are a powerful tool for diet, provenance, climate, and physiological reconstructions, but necessarily require well‐preserved specimens unaltered by postmortem diagenesis or conservation practices. This study examines the effects of Paraloid B‐72 and Butvar B‐98, two common consolidants used in field and museum conservation, on δ¹³C, δ¹⁵N, and δ¹⁸O values from bone collagen and hydroxyapatite. The effects of solvent removal (100% acetone, 100% ethanol, 9:1 acetone:xylenes, 9:1 ethanol:xylenes) and drying methods (ambient air, vacuum, oven drying at 80°C) were also examined to determine if bones treated with these consolidants can successfully be cleaned and used for stable isotope analyses. Results show that introduction of Paraloid B‐72 or Butvar B‐98 in 100% acetone or 100% ethanol, respectively, with subsequent removal by the same solvents and drying at 80°C facilitates the most successful removal of consolidants and solvents. The δ¹³C values in collagen, δ¹⁵N in collagen, δ¹⁸O in hydroxyapatite phosphate, and δ¹³C in hydroxyapatite structural carbonate were unaltered by treatments with Paraloid or Butvar and subsequent solvent removal. The δ¹⁸O in hydroxyapatite structural carbonate showed nonsystematic variability when bones were treated with Paraloid and Butvar, which is hypothesized to be a result of hydroxyl exchange when bones are exposed to consolidants in solution. It is therefore recommended that δ¹⁸O in hydroxyapatite structural carbonate should not be used in stable isotope studies if bones have been treated with Paraloid or Butvar. Am J Phys Anthropol 157:330–338, 2015. © 2015 Wiley Periodicals, Inc.