A resistive Q-switch for low-field NMR systems.

An NMR Q-switch was designed and constructed specifically for use with low-field NMR apparatus. This featured a comparatively simple resistive damping design. It served to reduce the r.f. probe ring-down time, and hence reduced the signal acquisition delay from 25 ms to 9 ms, on an Earth's magnetic field NMR system. The advantage of this earlier acquisition was demonstrated for both an aqueous suspension of iron oxide particles and using an NMR flow meter.

Reproductive performance of pubertal red deer (Cervus elaphus) hinds: effects of genetic introgression of wapiti subspecies on pregnancy rates at 18 months of age.

Low reproductive productivity of young red deer (Cervus elaphus) hinds on New Zealand deer farms appears to reflect high incidences of puberty failure at 16 months of age. This is despite the general attainment of average liveweights 15-25 kg in excess of the accepted minimum threshold for puberty in subspecies of western European origin (scoticus, elaphus and hippelaphus) that form the basis of the national herd. The present study tests the hypotheses that introgression of the larger North American wapiti subspecies (nelsoni, manitobensis and roosevelti) into breeding herds (1) can be assessed from morphological features of individuals, (2) that there is a relationship between the level of wapiti parentage and non-pregnancy rate at 18 months of age (a proxy for puberty failure) and (3) that minimum liveweight thresholds for puberty increase with increasing levels of wapiti parentage. A total of 4329 18-month-old hinds across four "red" deer farms in southern New Zealand were scanned for pregnancy status. Each hind was assigned a wapiti score (WS) as a subjective assessment of the obviousness of wapiti features. Various body measurements were additionally recorded for each hind. A hair sample was collected for DNA analysis (14 markers) to objectively assign subspecies pedigree (i.e. "Elkmeter") on a subset of 1258 individuals. A total of 506 (11.7%) hinds were not pregnant at 18 months of age with rates varying between 4.1 and 37.3% between farms and years. Mean WS differed significantly between farms and reflected the genetic management policy of each farm. WS was positively correlated to Elkmeter for each farm/year (<0.05) although regression slopes varied significantly. WS was able to be adjusted for these differences to assign a corrected WS (CWS) for all 4329 individuals that estimated the proportion wapiti parentage. Discriminant analysis of morphological variables relative to Elkmeter supported the first hypothesis and showed that shoulder height and body length were good indicators of the degree of wapiti parentage within individuals. This enabled the development of an objective estimate of wapiti parentage (EWP). The actual level of such parentage within herds ranged from <5 to >55%. There was a significant negative association between wapiti parentage and pregnancy, which was strongly influenced by liveweight, supporting the second and third hypotheses. This was manifest as marked displacement of pregnancy probability curves in relation to liveweight between genotype groups, particularly for those groups with >20% wapiti parentage. For example, predicted threshold liveweights required to achieve a 90% pregnancy rate for EWP values that represent 0, 10, 20, 30, 40 and 50% wapiti parentage were 81, 81, 85, 106, 127 and approximately 137 kg, respectively. Within the study herds, the majority of hinds of 0-20% wapiti parentage exceeded the predicted 90% threshold liveweights for their genotype cohort. However, hinds with higher levels of wapiti parentage generally fell below the predicted threshold for their genotype group. The data strongly suggest that under liveweight performance levels measured for red deer, hinds with >20% wapiti parentage are at high risk of puberty failure.

Influence of level of nutrition during late pregnancy on reproductive productivity of red deer I. Adult and primiparous hinds gestating red deer calves.

The present study aimed to relate feed intake of red deer hinds during late pregnancy to dam body condition, foetal development and calf growth. Across 3 years, multiparous (n=33) or primiparous (n=18) hinds with known conception dates were housed in individual pens from days 150-220 of pregnancy, during which time they were each offered one of three daily allowances of pelletised rations (11 MJME/kg DM; 16% CP): high (H; ad libitum), medium (M; approximately 30% less; multiparous hinds only) and low (L; approximately 50% less). Restricted intake levels were retrospectively calculated from the mean intake of H hinds in the previous week. Hinds were returned to pasture at day 220 and calving was closely monitored. Liveweights, body condition score (BCS), and lactation score (LS) of hinds were recorded weekly from day 130 of pregnancy until calves were weaned at 12 weeks of age. Calves were tagged and weighed at birth, and subsequently weighed at 7 and 12 weeks of age. Additionally, hinds in the first year of study underwent CT scans on days 150 and 215 of pregnancy to assess compositional changes of the dam and conceptus. Mean daily ad libitum intakes of H hinds increased from 1.8 to 2.0 kg DM (0.6-0.7 MJME/kg0.75) at around day 150 to 2.8-3.2 kg DM (0.8-0.9 MJME/kg0.75) by day 220. Those of M and L hinds peaked at 1.8 and 1.6 kg DM, respectively, by day 220. This was reflected in significant treatment effects on liveweight gain and change in BCS and LS by the time of calving. CT scans indicated a significant treatment effect by day 215 on the mass of hind tissues (fat and lean) and a non-significant trend on conceptus/foetal weights. Despite apparent differences in foetal growth trajectories, there were no discernable treatment effects on sex-adjusted birth weights. However, there was an unexpectedly wide spread in calving dates that reflected considerable variation in gestation length. Furthermore, gestation length was negatively correlated with change in hind liveweight (but not BCS) between days 150 and 220 of pregnancy for all groups of hinds (P<0.05). Of three neonatal calf mortalities, none were related to overweight (dystocia) or underweight (non-viability) calves. Subsequent growth rates (g/day) of surviving calves did not reflect prior treatment of their dams, although variation in birth date influenced weights on specific dates. It is concluded from this study that while variation in nutrition to hinds during the last trimester may strongly influence foetal development, under conditions of modest feed imbalance, variation in gestation length compensates to ensure optimisation of birth weight.

Influence of level of nutrition during late pregnancy on reproductive productivity of red deer (2) Adult hinds gestating wapitixred deer crossbred calves.

The present study aimed to relate feed intake of red deer hinds in the later stages of gestating wapitixred deer crossbred foetuses on dam body condition, gestation length, birth weight and calf growth. Multiparous hinds (N=18) conceiving at known dates to either wapiti (n=12) or red deer (n=6) sires were housed in individual pens from days 150-220 of pregnancy, during which time they were offered either ad libitum access to pelletised rations (n=6 crossbred-bearing hinds [HH] and n=6 red deer-bearing hinds [RH]) or a restricted offer (n=6 crossbred-bearing hinds [HL]) set at 70% of the average ad libitum intake of HH hind in the previous week. Hinds were returned to pasture at day 220 and calving was closely monitored. Liveweights, body condition score (BCS), and lactation score (LS) of hinds were recorded weekly from day 130 of pregnancy until calves were weaned at 12 weeks of age. Calves were tagged and weighed at birth, and subsequently weighed at 7 and 12 weeks of age. HH and RH hinds exhibited similar patterns and levels of MEI/kg0.75, which peaked at 7.8 MJME/kg0.75 at day 220. HL hinds peaked at approximately 5 MJME/kg0.75 and showed significantly lower rates of liveweight gain during pregnancy. Interestingly, both crossbred-bearing groups initiated mammary development in advance of the RH hinds. While there were significant effects of foetal genotype on mean gestation length (239 days versus 234 days for crossbred versus red deer) and mean birth weight (14.5 kg versus 10 kg), the nutritional contrast for gestation length of crossbred-bearing hinds (i.e. HH versus HL) was not significant but approached significance for birth weight (14.5 kg versus 11.9 kg; P=0.06). Regression analysis revealed weak relationships between changes in hind liveweight and gestation length (P>0.05) but a significant relationship with birth weight (P<0.05). However, change in hind BCS was significantly related to both gestation length and birth weight. Crossbred calves reared by HH hinds were 30% heavier at 7 and 12 weeks of age than the red deer calves. However, those reared by HL hinds were significantly lighter than their genotype contemporaries and only marginally heavier than the red deer calves. These results generally contrast with the previous studies on red deer hinds gestating red deer foetuses [Asher, G.W., Mulley, R.C., O'Neill, K.T., Scott, I.C., Jopson, N.B., Littlejohn, R. 2004. Influence of level of nutrition during late pregnancy on reproductive productivity of red deer, (1) Adult and primiparous hinds gestating red deer calves. Anim. Reprod. Sci., in press] and indicate that the genetically determined higher growth requirements of crossbred foetuses may override any mechanism of compensatory control of gestation length at the expense of calf birth weight. Furthermore, there were marked carryover effects of late gestational feeding on crossbred calf growth and their dam's BCS that highlight the high nutritional demands of lactation.

Genetic influences on reproduction of female red deer (Cervus elaphus) (1) seasonal luteal cyclicity.

This study compared the onset and duration of the breeding season of female red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (Cervus elaphus nelsoni) or Père David's (PD) deer (Elaphurus davidianus). In Trial 1 (1995), adult red deer (n=9), F1 hybrid wapiti x red deer (n=6) and maternal backcross hybrid PD deer x red deer (i.e., 14 PD; n=9) were maintained together in the presence of a vasectomised red deer stag for 12 months. They were blood-sampled daily or three times weekly so that concentration profiles of plasma progesterone could be used to identify the initiation, duration and cessation of luteal events. There was clear evidence of luteal cyclicity between April and September, with the transition into breeding associated with an apparent silent ovulation and short-lived corpus luteum (i.e., 6-12 days) in every hind. A significant genotype effect occurred in the mean time to first oestrus (P<0.05), with wapiti hybrids and 14 PD hybrids being 9 and 5 days earlier than red deer. Between six and nine oestrous cycles were exhibited by each hind, with no difference in mean cycle length (19.5-19.6 days) between genotypes (P0.10). The overall length of the breeding season was significantly longer for wapiti hybrids (143 days) than for either red deer (130 days) and 14 PD hybrids (132 days, P<0.05). In Trial 2 (1998), adult red deer (n=5), 14 PD hybrids (n=5) and F(1) PD x red deer hybrid (n=5) hinds were maintained together from mid-February (late anoestrus) to early May, in the presence of a fertile red deer stag from 1 April. Thrice-weekly blood sampling yielded plasma progesterone profiles indicative of the onset of the breeding season. Again, there was a significant genotype effect on the mean time to first oestrus (P<0. 05), with F(1) PD hybrids and 14 PD hybrids being 13 and 5 days earlier than red deer. However, conception dates were influenced by the timing of stag joining, and were not significantly different between genotypes. The results indicate genetic effects on reproductive seasonality. However, seasonality observed for PD x red deer hybrids more closely approximated that of red deer than PD deer.

Genetic influences on reproduction of female red deer (Cervus elaphus) (2) seasonal and genetic effects on the superovulatory response to exogenous FSH.

This study evaluated the influences of seasons and genotype on the superovulatory response to a standardised oFSH regimen in red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (C.e. nelsoni) or Père David's (PD) deer (Elaphurus davidianus). Adult red deer (n=9), F(1) hybrid wapiti x red deer (n=6), and maternal backcross hybrid PD x red deer (i.e., 14 PD hybrid; n=9) were kept together in the presence of a vasectomised stag for 13 months. At 6 weekly intervals, all hinds received a standardised treatment regimen used routinely to induce a superovulatory response in red deer hinds, with 10 consecutive treatments spanning an entire year. This involved synchronisation with intravaginal progesterone devices and delivery of multiple injections of oFSH (equivalent to 72 units NIH-FSH-S(1)). Laparoscopy to assess ovarian response was performed 6-7 days after the removal of the devices. Both season and genotype had significant effects on ovulation rate (OR) and total follicular stimulation (TFS) (P<0.05). For all the three genotypes, ovarian responses were highest from March to November (breeding season) and lowest in the period from December to January, inclusive. Mean OR for red deer hinds ranged from 3.7 to 1.8 during the breeding season, with no observable trend. All red deer hinds were anovulatory during December and January. A similar pattern occurred for 14 PD hybrids, although mean OR during the breeding seasons were twofold lower than for the red deer. For F(1) wapiti hybrids, the first two treatments in March and April resulted in the highest mean OR observed (15.6 and 11.7, respectively). Thereafter, mean values ranged between 6.3 and 4.7 for the remainder of the breeding season. Furthermore, mean OR of 3.0 and 0.5 were recorded in December and January, respectively. For the red deer and F(1) wapiti hybrids, between-hind variation in OR was not randomly distributed across the treatment dates, indicating that the individuals varied significantly in their ability to respond to oFSH, at least within a given season.In conclusion, the study has shown that relative to red deer, F(1) wapiti hybrid hinds exhibit a higher sensitivity to oFSH, whereas 14 PD hybrid hinds have a lower sensitivity. However, individual variation within genotype was very marked. A seasonal effect was apparent for all genotypes, although some F(1) wapiti hybrid hinds exhibited ovulatory responses throughout the year.

Ultrasonographic monitoring of antral follicle development in red deer (Cervus elaphus).

Ovarian follicular dynamics were monitored in 12 surgically modified red deer hinds (ovaries adhered to vaginal wall) by transvaginal real-time ultrasonography during the luteal cycle, anoestrus and induction of superovulation. All 12 hinds showed evidence of regular luteal (plasma progesterone) cyclicity during the breeding season, although luteal tissue was not observed on the ultrasonograms. During the normal luteal cycle (14-22 days) total numbers of follicles > 3 mm did not vary significantly by day (range of means: 1.8-3.4; P > 0.05). A single large (> or = 6 mm) follicle was usually present on all days except immediately after ovulation (day 0). However, the appearance of new follicles (> or = 3 mm) was not random, and was greatest on day 1 and day 14 (P < 0.05). Tracking of individual follicles revealed irregular waves of emergence and disappearance of the largest follicle, with either one (n = 1), two (n = 3) or three (n = 5) waves observed across nine luteal cycles. New follicles (> or = 3 mm) emerged after regression or ovulation of a large follicle, suggesting a dominance effect. There were no significant differences in the overall mean numbers of follicles during early, mid- and late anoestrus (September, November and April, respectively) but follicle turnover was more rapid during mid-anoestrus as evidenced by a significantly greater number of new small (> 3 mm) follicles (P < 0.001). Administration of superovulatory doses of ovine FSH during the breeding season resulted in a marked increase in the appearance of new follicles within 48 h of initiation of the injection regimen. By termination at 96 h, the time of progesterone withdrawal, the mean number of follicles > 3 mm was significantly higher than for control hinds (9.8 versus 3.0; P < 0.0001). While most follicles ovulated progressively 2-7 days later, about 40% persisted beyond this period. The study demonstrated the presence of discrete patterns of antral follicle growth and regression during the breeding and non-breeding seasons, with the luteal cycle characterized by a variable number (1-3) of dominant follicle waves. Anoestrus represents a period of dynamic changes in follicular turnover.

Seasonal patterns of luteal cyclicity in young red deer (Cervus elaphus) and sambar deer (Cervus unicolor).

Seasonal onset of pubertal ovulation and incidence of luteal cyclicity was assessed from plasma progesterone profiles over 15 months for tame red deer (n = 7) and sambar deer (n = 7) hinds. Seasonal responses to photoperiod were determined from plasma prolactin profiles. All red deer attained puberty at 17-18 months of age in May-June and expressed 3-6 luteal cycles of length 20.0+/-10.4 days (mean+/-s.e.m.) over 52-102 days. Six sambar deer attained puberty at 7-19 months of age, between August and December. Duration of luteal cyclicity was variable. While one animal remained continuously cyclic for 13 months, most entered anoestrus between November and February. The mean length of the luteal cycle was 17.2+/-0.3 days. While red deer exhibited strongly seasonal patterns of prolactin secretion, sambar deer showed no such seasonal trends. The data collectively indicate that young sambar hinds at temperate latitudes exhibit loosely defined patterns of reproductive seasonality that are 4-6 months out of phase with those of red deer, although some individuals may be non-seasonal. Failure to express seasonal patterns of prolactin secretion indicates that sambar deer may not perceive photoperiodic cues to the same extent as do red deer.

Comparison of seasonal changes in reproductive parameters of adult male European fallow deer (Dama dama dama) and hybrid Mesopotamian x European fallow deer (D. d. mesopotamica x D. d. dama).

In a study, aimed at comparing seasonal reproductive development of European fallow deer (Dama dama dama) with Mesopotamian (D. d. mesopotamico) x European F1 hybrids, five adult males of each genotype, which had been raised together since birth, were maintained as a bachelor group. Morphometric (body weight, neck circumference and testis diameter), endocrine (plasma testosterone concentrations) and seminal (ejaculate volume, spermatozoa per ejaculate and spermatozoa motility) parameters were recorded at fortnightly or monthly intervals for a 15-month period, and antler status was noted daily during the general periods of casting and velvet stripping. In addition, two bucks of each genotype were blood sampled via indwelling jugular catheters every 30 min for 24-h periods on five occasions (2-3 months intervals) during the year, and plasma was analysed for concentrations of testosterone and LH. Parameter profiles of the two genotypes were compared by global and time series ante-dependence covariance analysis to investigate overall profile similarity and the seasonal nature of any observed differences. Plasma hormone profiles from high-frequency blood sampling were subjected to PULSAR analysis to determine pulse frequency and amplitude. Throughout the study hybrid males were approximately 30% heavier than European males. However, both genotypes exhibited dramatic but parallel patterns of body weight change (global P = 0.054). Neck circumference was correlated with body weight throughout (P < 0.05), with similar regression slopes between the genotypes at any sampling time (P > 0.10). Covariance adjustment to a common initial body weight was performed to eliminate the effects of large body weight differences on muscle hypertrophy and regression. While profiles of corrected neck circumference were significantly different at the global level (P < 0.01), analysis by time revealed differences occurring only during the latter period of muscular regression in spring. However, profiles of other parameters, including testis diameter, plasma testosterone concentrations, spermatozoa per ejaculate and percentage motile spermatozoa, exhibited significant displacement between genotypes (global P < 0.05) evident as 2-4 weeks advancement in the sexual development (late summer/autumn) and quiescence (spring) phases for hybrid males relative to European males. Furthermore, mean dates of antler casting and velvet stripping were significantly earlier by 2-3 weeks for hybrid males than European males (P < 0.05). High frequency blood sampling revealed markedly seasonal patterns of secretion of testosterone and LH, with hybrid males exhibiting an apparent earlier onset of high-amplitude testosterone 'surges' in February (late summer) compared to those occurring in April (autumn) for European males. When viewed collectively, the data indicate strongly that the Mesopotamian influence is evident in the earlier attainment of sexual development and fertility in late summer and autumn, and earlier onset of sexual quiescence in spring. This is in accord with anecdotal information on earlier reproductive patterns in purebred Mesopotamian fallow deer.

The binding of oxidised coenzyme to bovine-liver glutamate dehydrogenase studied by circular-difference spectroscopy.

1. The binding of NAD+ to glutamate dehydrogenase may be followed quantitatively by titration, using high-sensitivity circular dichroism (CD) difference spectroscopy. 2. The CD of the bound coenzyme in the binary complex E . NAD closely resembles that of bound ADP, although the affinity is much lower, being 350-fold less for NAD+ at 20 degrees C in 0.1 M phosphate, pH 7. 3. A family of CD spectra may be analysed by unconstrained linear regression assuming only three components: free enzyme, free coenzyme, and a single binary complex, E . NAD. 4. Taking the molar CD of bound ADP as representing the molar CD of the adenine chromophore of bound NAD+, the linear regression shows the formation of a simple 1 : 1 complex E . NAD with Kd = 0.72 mM in a simple binding process without positive or negative cooperativity. 5. NADP+ binding is more than 10-fold weaker than NAD+ binding. 6. From the similarity of the CD of bound ADP and bound NAD+ it is probable that NAD+, in forming a simple binary complex, binds preferentially at the regulatory (adenine nucleotide) binding site (site II). 7. Direct evidence has been obtained for the binding of a second molecule of NAD+ to the ternary complex E . NAD . glutarate. This process occurs with low affinity and is probably also located at the adenine regulatory site. 8. This second-site binding of NAD+ may contribute to the phenomena of non-Michaelis-Menten kinetics and apparent negative homotropic interactions in the binding of NAD+, previously attributed to subunit-subunit cooperative interactions.