Seminalplasmin: A protein with many biological properties

Proteins present in the seminal plasma of mammals are known to influence functions associated with ejaculated spermatozoa such as motility, capacitation, acrosome reaction and fertilising ability. The proteins isolated and characterised so far influence only one of the above functions of spermatozoa. Seminalplasmin, a protein isolated from the seminal plasma of bull is exceptional in that it influences many of the above spermatozoal functions. It is also a potent antimicrobial protein and capable of lysing microbial and mammalian cells. The physiological function of seminalplasmin as nature's own antifertility agent is discussed.     

Performance of Two Fruit Fly (Diptera: Tephritidae) Pupal Parasitoids (Coptera haywardi [Hymenoptera: Diapriidae] and Pachycrepoideus vindemiae [Hymenoptera: Pteromalidae]) under Different Environmental Soil Conditions

We evaluated the performance of Coptera haywardi (Ogloblin) (Diapriidae) and Pachycrepoideus vindemiae (Rondani) (Pteromalidae), both hymenopteran pupal parasitoids of Anastrepha spp. (Diptera: Tephritidae). Performance was studied by manipulating the following environmental conditions in the laboratory: (1) soil type, (2) soil moisture content, (3) soil compaction, and (4) depth at which pupae were buried in the soil. There were two experiments: in the first, exposure time of pupae was held constant and in the second, it varied. In the first experiment, C. haywardi was significantly more effective than P. vindemiae in parasitizing fly pupae. With exposure time held constant (36 h), only soil type and pupal burial depth were significantly related to parasitism rates. While P. vindemiae only parasitized pupae located on the soil surface, C. haywardi attacked pupae that were buried up to 5 cm deep, performing better in clayey than in loamy soil. In the second experiment, exposure time (24, 36, 48, and 72 h) had no significant effect on parasitism rates, but soil type did. P. vindemiae again only attacked pupae on the soil surface while C. haywardi was also able to parasitize pupae that were buried up to 5 cm deep. We conclude that C. haywardi represents a viable candidate to replace the environmentally unfriendly P. vindemiae in augmentative biological control programs against fruit flies.     

Influence of activity in a heterogeneous environment on the dynamics of fish growth: an individual-based model of roacl

A spatio-temporal individual-based model (IBM), including bioenergetic principles, is used to investigate how energy costs coupled to activity represent a variable fraction in a heterogeneous environment and how this is related to another energetic criterion, the potential individual growth, under the conditions of a structured environment. With this approach, it is possible to connect simulated spatio-temporal activity patterns with the energetic needs required for these activities. By using simple foraging rules and a modified random walk model it is possible to reproduce spatial distributions and length frequency distributions. The simulated spatial distribution of roach Rutilus rutilus in Lake Belau, Germany, results in a mean weekly activity multiplier [(standard metabolic rate + activity costs) (standard metabolic rate)⁻¹] of 1–9 with deviations >100% during a simulated year. These deviations are of key importance to differences in the growth rate of individual simulated roach.     

The haemagglutination activity in the different developmental stages and changes of this activity caused by analogues of insect hormones in two members of the Culex pipiens complex of mosquitoes

Abstract. Haemagglutination activity was studied in last larval instars, pupae and adults of both sexes of the Culex pipiens mosquito complex. In females of Culex pipiens quinquefasciatus Say, an anautogenous member of C. pipiens complex, activity was detected in the homogenate of the head‐thorax complex, gut and remaining abdomen (after removing the gut), before and after sucking water, glucose solution or blood. Similar investigations were made in females of autogenous Culex pipiens molestus Forskal, a member of the same mosquito complex. The results were compared with data obtained for males of these subspecies, plus the larvae and pupae. The results show that haemagglutination activity in adult females depends not on the sucking of blood, but on the age of the females. In newly emerged females, the level of activity was very low, but after 24 h or 48 h of activity was highly enhanced, even in females that had no possibility to suck water or other liquids including blood. Furthermore, in C. p. molestus, the haemagglutination activity does not change in hungry or engorged females, and a high level of activity was found in the gut of last larval instars, a developmental stage that never takes blood. Treatment with methoprene reduces haemagglutination activity in both sexes, but 20‐hydroxycdysone application decreased activity in the gut of females. It is suggested that haemagglutination activity may be regulated indirectly by the endocrine system. The possibility that haemagglutination activity may depend on some aspect of the digestive system that has no direct connection to blood uptake is discussed. In addition, the activity may be important not only for the elimination of infections, but also for the processing of food and the utilization and transport of nutrients.     

Daily activity of the pest slug Arion lusitanicus under laboratory conditions

The daily activity of the slug Arion lusitanicus was studied using time‐lapse video analysis in the laboratory. Under constant temperature (18°C) and 16–h photoperiod, the activity of slugs was measured in half‐hourly periods as locomotor activity, feeding or resting. Track lengths were determined using image analysis. Locomotion of A. lusitanicus was greatest at 5:30, 1.5 h after sunrise, and at 20:30, 1 h after sunset; least locomotor activity occurred between 13:00 and 14:00. The mean distance travelled by A. lusitanicus in 24 h was 10.8 m. The largest slug was the most active and the smallest the least. Slugs spent 68% of 24 hours resting, mainly under artificial shelter traps, 27% in locomotion and 4% feeding. Feeding occurred mainly during the hours of dakness (76%). All categories of behaviour investigated varied greatly between individuals and also between times of day. Homing to artificial shelters and other roost sites was regularly observed within 24 h (41%), but decreased considerably thereafter. The behavioural patterns proved to be in agreement with those found in a previous field investigation and are therefore also discussed with a view to their importance in pest control.     

VARIATION IN ALCOHOL DEHYDROGENASE ACTIVITY AND FLOOD TOLERANCE IN WHITE CLOVER,TRIFOLIUM REPENS

Flooding results in induction of anaerobic metabolism in many higher plants. As an important component of anaerobic energy production, alcohol dehydrogenase (ADH) activity increases markedly in response to flooding in white clover, Trifolium repens. Significant inter-individual variation in flood-induced ADH activity exists in natural populations of T. repens. The genetic basis of this variation was analyzed by offspring-midparent regression of data from 75 greenhouse reared families; the estimated heritability of flood-induced ADH activity was 0.55 (±0.13). Genetic variation in flood-induced ADH activity has pronounced effects on physiological response and flood tolerance in this species. ADH activity is positively correlated with the rate of ethanol production, indicating that observed in vitro activity differences are manifested in in vivo physiological function. T. repens plants with higher ADH activities during flooding have greater flood tolerance (measured as growth rate when flooded/unflooded growth rate). Variation in ADH activity during flooding accounts for more than 79% of the variance in flood tolerance. On the basis of a limited field survey of populations occupying three sites differing in exposure to flooding conditions, individuals from site C, the most frequently flooded site, expressed significantly higher average ADH activity when flooded than individuals from site A, a site with no history of flooding. Since ADH activity levels are not correlated with electrophoretic mobility variation in T. repens, this work supports previous suggestions that regulatory variation in enzyme activity may play a central role in biochemical adaptations to environmental stress.     

The effect of salty diets and gradual transfer to sea water on osmotic adaptation, gill Na+, K+-ATPase activation, and survival of brook charr, Salvelinus fontinalis, Mitchill

The intensity and duration of the period of osmotic disturbance during introduction of brook charr into sea water were decreased by introducing the fish according to a gradient of salinity over a period of 6 days. Survival in summer increased from 25 to 90% with the use of a salinity gradient. However, kinetics and levels of activation of the gill Na⁺, K⁺-ATPase were not affected by the mode used for introducing brook charr into sea water. Neither was its level of activity modified by the use of a salted diet when the fish were in fresh water. The addition of 8 and 12% of salt to the diet prevented the plasma electrolyte surge of concentrations during the first days in sea water. In very cold water, survival rate was also drastically improved by giving an 8% salted diet during the 6 weeks preceding the introduction into sea water. These results show that both salty diets and exposure to brackish water during 6 days help brook charr face osmotic stress and improve their survival rate when introduced into full-strength sea water. The combined use of these preconditioning strategies might facilitate rearing this species in sea cages or silos.     

Fine structural recognition specificities of IgE antibodies distinguishing amoxicilloyl and amoxicillanyl determinants in allergic subjects.

IgE antibodies in the sera of subjects allergic to beta-lactam antibiotics detect a spectrum of specificities ranging from side-chain groups to an entire penicillin or cephalosporin molecule. In addition to such structural heterogeneity of allergenic determinants, IgE antibodies in the sera of different allergic subjects show heterogeneous recognition responses. Detailed immunochemical studies were carried out on the sera of penicillin-allergic subjects that showed selective and unexpected reactions with the frequently prescribed penicillin, amoxicillin. Antibodies from one subject reacted only with the amoxicilloyl determinant while IgE from another subject showed multiple reactivity with penicilloyl and penicillanyl determinants of different penicillins but not with the amoxicilloyl determinant. Quantitative hapten inhibition studies revealed that the combining sites of the former antibodies were complementary to amoxicillin in a form that permits binding to the hydroxyaminobenzyl side-chain and the thiazolidine ring carboxyl. These conditions are satisfied with the drug in the '-oyl' but not in the '-anyl' form which involves linkage through the 2-carboxyl of the thiazolidine ring. With the second serum, adsorption studies showed that the wide-ranging reactivity of IgE was due to a single population of antibodies that detected a common specificity on the different penicillins. Combining site studies revealed clear recognition of the benzyl portion of the side-chain of benzylpenicilloyl, benzylpenicillanyl, ampicilloyl, ampicillanyl and amoxicillanyl determinants when free antibody access to the side-chain was possible but little or no recognition of the ring hydroxyl of amoxicillin. Such uninhibited access may not occur, however, when amoxicillin is conjugated in the '-oyl' form since opening the beta-lactam ring allows increased flexibility and rotation of the molecule and the possibility of close association of the hydroxyaminobenzyl side-chain of amoxicillin with the linked peptide carrier. In such close steric association, H-bonding involving the ring hydroxyl and amino acids of the carrier may prevent antibody access to the side-chain region of the amoxicilloyl determinant.     

Soil carbon sequestration and land‐use change: processes and potential

When agricultural land is no longer used for cultivation and allowed to revert to natural vegetation or replanted to perennial vegetation, soil organic carbon can accumulate. This accumulation process essentially reverses some of the effects responsible for soil organic carbon losses from when the land was converted from perennial vegetation. We discuss the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land‐use and soil management. We review literature that reports changes in soil organic carbon after changes in land‐use that favour carbon accumulation. This data summary provides a guide to approximate rates of SOC sequestration that are possible with management, and indicates the relative importance of some factors that influence the rates of organic carbon sequestration in soil. There is a large variation in the length of time for and the rate at which carbon may accumulate in soil, related to the productivity of the recovering vegetation, physical and biological conditions in the soil, and the past history of soil organic carbon inputs and physical disturbance. Maximum rates of C accumulation during the early aggrading stage of perennial vegetation growth, while substantial, are usually much less than 100 g C m^?2 y^?1. Average rates of accumulation are similar for forest or grassland establishment: 33.8 g C m^?2 y^?1 and 33.2 g C m^?2 y^?1, respectively. These observed rates of soil organic C accumulation, when combined with the small amount of land area involved, are insufficient to account for a significant fraction of the missing C in the global carbon cycle as accumulating in the soils of formerly agricultural land.